User association in small cell heterogeneous network with downlink sum rate

In this paper, a satellite-aerial integrated computing (SAIC) architecture in disasters is proposed, where the computation tasks from two-tier users, i.e., ground/aerial user equipments, are either locally executed at the high-altitude platforms (HAPs), or offloaded to and computed by the Low Earth Orbit (LEO) satellite. With the SAIC architecture, we study the problem of joint two-tier user association and offloading decision aiming at the maximization of the sum rate. The problem is formulated as a 0-1 integer linear programming problem which is NP-complete. A weighted 3-uniform hypergraph model is obtained to solve this problem by capturing the 3D mapping relation for two-tier users, HAPs, and the LEO satellite. Then, a 3D hypergraph matching algorithm using the local search is developed to find a maximum-weight subset of vertex-disjoint hyperedges. Simulation results show that the proposed algorithm has improved the sum rate when compared with the conventional greedy algorithm.

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Energy Efficiency Maximization of Dynamic CoMP-JT Algorithm in Dense Small Cell Networks

Wireless Communications and Mobile Computing ◽

10.1155/2018/8572489 ◽

2018 ◽

Vol 2018 ◽

pp. 1-7

Author(s):

Xuefei Peng ◽

Jiandong Li ◽

Yifei Xu

Keyword(s):

Energy Efficiency ◽

Power Allocation ◽

Optimal Solution ◽

Small Cell ◽

Base Stations ◽

Maximization Problem ◽

Second Phase ◽

User Association ◽

Coordinated Multipoint ◽

Convex Problem

We firstly formulate the energy efficiency (EE) maximization problem of joint user association and power allocation considering minimum data rate requirement of small cell users (SUEs) and maximum transmit power constraint of small cell base stations (SBSs), which is NP-hard. Then, we propose a dynamic coordinated multipoint joint transmission (CoMP-JT) algorithm to improve EE. In the first phase, SUEs are associated with the SBSs close to them to reduce the loss of power by the proposed user association algorithm, where the associated SBSs of each small cell user (SUE) form a dynamic CoMP-JT set. In the second phase, through the methods of fractional programming and successive convex approximation, we transform the EE maximization subproblem of power allocation for SBSs into a convex problem that can be solved by proposed power allocation optimization algorithm. Moreover, we show that the proposed solution has a much lower computational complexity than that of the optimal solution obtained by exhaustive search. Simulation results demonstrate that the proposed solution has a better performance.

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Investigation on Distributed Joint Optimization of User Association and ICIC Based on PF Criteria in Small Cell Deployments

2019 International Symposium on Intelligent Signal Processing and Communication Systems (ISPACS) ◽

10.1109/ispacs48206.2019.8986295 ◽

2019 ◽

Author(s):

Takuya Matsumoto ◽

Nobuhiko Miki

Keyword(s):

Small Cell ◽

Joint Optimization ◽

User Association

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

Mobile Information Systems ◽

10.1155/2019/6871378 ◽

2019 ◽

Vol 2019 ◽

pp. 1-12 ◽

Cited By ~ 2

Author(s):

Jing Gao ◽

Qing Ren ◽

Pei Shang Gu ◽

Xin Song

Keyword(s):

Energy Efficiency ◽

Optimization Method ◽

Base Station ◽

Small Cell ◽

Base Stations ◽

User Association ◽

User Mobility ◽

Efficient Design ◽

Widespread Application ◽

Cell Base

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.

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