User Distribution Scenario Research Articles

Deep Reinforcement Learning Evolution Algorithm for Dynamic Antenna Control in Multi-Cell Configuration HAPS System

In this paper, we propose a novel Deep Reinforcement Learning Evolution Algorithm (DRLEA) method to control the antenna parameters of the High-Altitude Platform Station (HAPS) mobile to reduce the number of low-throughput users. Considering the random movement of the HAPS caused by the winds, the throughput of the users might decrease. Therefore, we propose a method that can dynamically adjust the antenna parameters based on the throughput of the users in the coverage area to reduce the number of low-throughput users by improving the users’ throughput. Different from other model-based reinforcement learning methods, such as the Deep Q Network (DQN), the proposed method combines the Evolution Algorithm (EA) with Reinforcement Learning (RL) to avoid the sub-optimal solutions in each state. Moreover, we consider non-uniform user distribution scenarios, which are common in the real world, rather than ideal uniform user distribution scenarios. To evaluate the proposed method, we do the simulations under four different real user distribution scenarios and compare the proposed method with the conventional EA and RL methods. The simulation results show that the proposed method effectively reduces the number of low throughput users after the HAPS moves.

Resource Allocation for Network Slicing in RAN Using Case-Based Reasoning

As a key technology of 5G, network slicing can meet the diverse needs of users. In this research, we study network slicing resource allocation in radio access networks (RAN) by case-based reasoning (CBR). We treat the user distribution scenario as a case and stored a massive number of cases in the library. CBR is used to match a new case with cases in the case library to find similar cases and determine the best slice bandwidth ratio of the new case based on these similar cases. In the matching process, the k-nearest neighbors (KNN) algorithm is used to retrieve similar cases, the nearest k neighbors being determined by considering sparsity reduction and locality-preserving projections. Although only an initial study, the results confirm that the proposed architecture is capable of allocating resources efficiently in terms of prediction error and computational cost.

QoS-Aware Energy-Efficient MicroBase Station Deployment for 5G-Enabled HetNets

The increasing energy consumption is a legacy of the fast improvement of ICT (Information and Communication Technology). It is also contrary to the current energy conservation and emission reduction concept. There are several reasons for high energy consumption. Among them, we find that the increase in base station density of the 5G heterogeneous network (5G HetNets) is prominent. We present a micro base station deployment strategy in 5G HetNets for obtaining high energy efficiency. It optimizes target values as are trade-offs at different user distribution probabilities to improve adaptation to different user distribution scenarios. An energy deployment algorithm based on high efficiency for micro base stations is considered as jointly optimizing micro base station’s number, deployment location, and power configuration. Simulation results show that the proposed combinatorial optimization strategy effectively improves the system energy efficiency compared to the deployment method, regardless of the power factor. Moreover, it verifies that the micro base station power affects the energy efficiency in HetNets.

A Fast Heuristic for Gateway Location in Wireless Backhaul of 5G Ultra-Dense Networks

In 5G ultra-dense networks, a distributed wireless backhaul is an attractive solution for forwarding traffic to the core. The macro-cell coverage area is divided into many small cells. A few of these cells are designated as gateways and are linked to the core by high-capacity fiber optic links. Each small cell is associated with one gateway and all small cells forward their traffic to their respective gateway through multi-hop mesh networks. We investigate the gateway location problem and show that finding near-optimal gateway locations improves the backhaul network capacity. An exact p-median integer linear program is formulated for comparison with our novel K-GA heuristic that combines a Genetic Algorithm (GA) with K-means clustering to find near-optimal gateway locations. We compare the performance of K-GA with six other approaches in terms of average number of hops and backhaul network capacity at different node densities through extensive Monte Carlo simulations. All approaches are tested in various user distribution scenarios, including uniform distribution, bivariate Gaussian distribution, and cluster distribution. In all cases, K-GA provides near-optimal results, achieving average number of hops and backhaul network capacity within 2% of optimal while saving an average of 95% of the execution time.

Implementation and Evaluation of Novel Architecture Using Optical Wireless for WLAN Control Plane

We propose a novel wireless control system architecture that divides the wireless service area into smaller optical cells and centrally controls the user equipment (UE) connections under each optical cell. The proposal transmits via IoT smart lighting an optical identifier (ID) specifying connection information to the UE with illuminance sensor. The received optical ID indicates the optimum connection destination. Two solutions are proposed to overcome the hardware restrictions faced by optical ID transmission/reception. Oversampled edge-excluded receiving scheme (OE) reduces the error rate; the signal is oversampled and each window subjected to majority decision. Optical ID reception with lower error rate than conventional approach is realized with a minimum received illuminance of just 8.5 lx (background illuminance 226.67 lx) and a modulation factor of 7 %. Fast optical ID authentication (FA) reduces the authentication cycle preceding optical ID reception by performing correlation calculation between the cyclic matrix and an optical ID list. FA shortens the authentication cycle by 62.5 % (1200 ms to 450 ms). Furthermore, an optical cell control algorithm (ScanLine-based/MinDist-based) is proposed to offset the deterioration in network quality created by non-uniform UE distribution. ScanLine-based algorithm controls optical cells in scanning line manner, while MinDist-based favors optical cells with the minimum distance from the access point (AP). It is confirmed that with an optical cell radius of 5 m or less, the capacity difference per user is reduced compared to the existing RSSI-based alternative while reducing the deterioration of total capacity in extremely biased user distribution scenarios.

Spatial Resource Management in LEO Satellite

Low Earth Orbit (LEO) satellite communication systems are known to have complicated spatial resource management. The problem occurs because of the impossibility to realize fully digital beamforming since its hardware implementation consumes too much power of the on-board battery. On another hand, analog beamforming can not provide enough system coverage in realistic user distribution scenarios. In this paper, we justify the choice of the hybrid multi-beamforming structure for some realistic user distributions. Such a structure guarantees enough coverage with minimal power consumption. For this structure, we propose a new spatial resource allocation intended to minimize handovers and to simplify the calculation of the time user spends inside each satellite beam spot. Numerical results with real system parameters are provided to confirm feasibility.

Simulation analysis of key technology optimization of 5G mobile communication network based on Internet of Things technology

With the rapid development of mobile Internet and Internet of Things business, the 5G mobile communication process has been accelerated. This article summarizes the Internet technology under 5G mobile communication, analyses the connotation of Internet of Things, and studies the integration of 5G mobile communications and Internet of Things technology. Through the analysis and discussion of the new possibilities in the Internet of Things era under 5G mobile communication technology, the research shows that the simulation analysis combined with the cell breathing technology and the base station dormancy technology aims to decrease the energy consumption of the base station under the premise of ensuring the communication quality, thereby improving the network energy efficiency. Research shows that in the dense and uniform user distribution scenario, the power consumption has a small decrease due to the increase of power consumption, but the system capacity is significantly improved and the communication quality is improved. It can ensure the user’s fairness and system capacity to achieve, and meet the rate requirements of different users. The analog results verify the accuracy of the theoretical analysis.

Rate selection for wireless multicast system adopting incremental redundancy type hybrid-ARQ

We propose a rate selection method in wireless multicast systems where an incremental redundancy type hybrid automatic repeat request (HARQ-IR) scheme is employed under Rayleigh block-fading channels. We aim at maximizing the long-term average transmission rate (LATR) while the maximum number of retransmissions is limited to L — 1 and the probability that at least one user fails to decode a message within L (re)transmissions is limited to e. We consider two user-distribution scenarios: 1) Receivers are located at the same distance from the source and 2) receivers are uniformly distributed in a circular cell. For the former scenario, we derive two closed-form approximations for the LATR. Among the two, the simpler one is expressed as $\mu - {{Q^{-1}(1-0.5^{1/U})\sigma}\over{\sqrt L}}$ for a large L value where U, μ, σ, Q denote the number of receivers, the ergodic capacity, and the deviation of the mutual information for one HARQ round, and the complementary Gaussian cumulative distribution function, respectively. We also analyze the second scenario using point mass approximation. We show that the HARQ-IR scheme outperforms the conventional fixed-length coding and Chase-combining type HARQ schemes in wireless multicast network for both scenarios.

Semi-Blind Interference Alignment Techniques for Small Cell Networks

This paper investigates the application of blind and semi-blind interference alignment methods in clustered small cell networks. First, we examine two simple straightforward extensions of blind interference alignment and observe that neither of them is uniformly superior under all user distribution. Then, we exploit the location information of the users and base stations (BSs) in the cluster to define the semi-blind interference alignment problem, whose objective function is to minimize the supersymbol length by grouping the users that can be served in the same time slot. We show that this problem is NP-hard and propose two heuristic centralized algorithms that can provide effective solutions. The first scheme, top-level semi-blind supersymbol design, employs a grouping indicator matrix to determine the supersymbol while the second scheme, ordered semi-blind supersymbol design, constructs the supersymbol in an ordered and greedy fashion. Finally, we propose a more decentralized scheme which does not have the location information of all users and BSs in the cluster, but the BS utilizes the long-term SINR values, obtained via feedback, of each user it serves. By numerical simulations, we show that the proposed semi-blind algorithms perform uniformly better than pure blind interference alignment schemes for any possible user distribution scenario.

Uplink outage performance of linear cellular networks with non‐uniform user distribution

The Wyner model has been extensively used in the literature for analysing cellular networks. Recent studies show that when compared with a grid-based model, this simple model fails to capture key features of a cellular network under different scenarios. Without increasing complexity, a linear network model which uses an average user distance and considers a non-uniform user distribution scenario within cells is proposed. Simulation results show that despite the simplicity, the proposed model can provide a close insight when compared with a grid-based model.

Path-loss Based Power Suppression for Spectral and Energy Efficient Inter-cell Interference Coordination

The inter-cell interference problem is a key challenge in OFDMA-based cellular networks because it significantly decreases the throughput of the users at the cell edge. Mitigating this problem requires an inter-cell interference coordination (ICIC) scheme that divides the spectrum into a power constant band and a power limited band for the cell edge users. Overall, static ICIC or frequency reuse schemes are effective when users are uniformly distributed across the network, whilst non-uniform user distributions suggest semi-static ICIC schemes where the power levels in the power limited bands are effectively set based on the interference situation from neighboring cells. In this paper we define a method that uses path-loss statistical measures to describe the non-uniform distribution between adjacent cells. Based on this method, we devise a new distributed algorithm that derives the suppression levels of transmit power a cell may set at a neighboring cell’s cell edge band based on the path-loss to the cell edge users of that neighboring cell. Our algorithm is evaluated by means of simulations and compared to reference frequency reuse schemes based on a non-uniform user distribution scenario where users are distributed in clusters. Simulation results show that the power suppression levels derived by our algorithm greatly improve spectral and energy efficiency as compared to 7-reuse and 1-reuse schemes respectively. It is also shown that our algorithm exploits the non-uniformity in the user distribution to improve the user throughput of cell edge users without any losses in the user throughput of the cell center users. Keywords: ICIC, interference coordination, frequency partitioning, orthogonal frequency division multiplexing (ofdm), soft frequency reuse system capacity, 3GPP LTE standardization.

Cross Layer Design for Efficient Video Streaming over LTE Using Scalable Video Coding

Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) offers high data rate capabilities to mobile users, and network operators are trying to deliver a true mobile broadband experience over LTE networks. Mobile TV and Video on Demand (VoD) are expected to be the main revenue generators in the near future, and efficient video streaming over wireless is the key to achieve this goal. Video services use both unicast and multicast video transmission based on its applications. Enhanced Multimedia Broadcast/Multicast Service (EMBMS) is defined in 3GPP specification to support download delivery and streaming delivery to group users in LTE mobile networks. In 3GPP Release 8 specification, the EMBMS transmission is classified into single-cell transmission and MBSFN (Multicast Broadcast Single Frequency Network) transmission. In this paper, we propose a Scalable Video Coding (SVC) based video streaming scheme with dynamic adaptations and a scheduling scheme based on channel quality for unicast and multicast video transmissions. In our proposed unicast scheme, Channel Quality Indicator (CQI) feedbacks from User Equipment’s (UE) are used for dynamic adaptations and scheduling. Cross layer signaling between Medium Access Control (MAC) and Real Time Transport (RTP) protocols is used to achieve the channel dependent adaptation for unicast in video server. Simulation results for unicast indicate improved video quality for more number of users with reduced bit rate video traffic. Approximately 13% video quality gain is observed for users at the cell edge using this adaptation scheme. We have also proposed a scheduling scheme for multicast over MBSFN networks. This scheme optimizes the radio spectrum allocation by adaptive modulation and coding (AMC) and frequency scheduling based on distribution of users in different channel quality regions. Through simulations we demonstrate that spectrum savings in the order of 72 to 82% is achievable in different user distribution scenarios with our proposed scheme.