Xiaowei Qin

Proportional-fair downlink resource allocation in OFDMA-based relay networks

In this paper, we consider resource allocation with proportional fairness in the downlink orthogonal frequency division multiple access relay networks, in which relay nodes operate in decode-and-forward mode. A joint optimization problem is formulated for relay selection, subcarrier assignment and power allocation. Since the formulated primal problem is nondeterministic polynomial time-complete, we make continuous relaxation and solve the dual problem by Lagrangian dual decomposition method. A near-optimal solution is obtained using Karush-Kuhn-Tucker conditions. Simulation results show that the proposed algorithm provides superior system throughput and much better fairness among users comparing with a heuristic algorithm.

Utility-based resource allocation in OFDMA relay networks with service differentiation

In this paper, we investigate the utility-based resource allocation problem in OFDMA relay networks with service differentiation, where Rate Constraint (RC) and Best Effort (BE) services are supported. Our objective of resource allocation is to maximize the sum utility of BE service users, while guaranteeing that the utility of each RC service user is equal to one. A joint optimization problem for relay selection, subcarrier assignment and power allocation is formulated. Since the problem cannot be solved directly, we make continuous relaxation and solve it by La-grangian dual method. The optimal allocation strategy is obtained using Karush-Kuhn-Tucker (KKT) conditions. As it is difficult to converge to the optimal solution, thus we further present a heuristic resource allocation algorithm with low complexity. Simulation results show that our proposed algorithm achieves higher utility of BE users and lower outage probability of RC users, and also yields a good tradeoff between system throughput and user fairness.

Optimal matching between energy consumption of Base Stations and traffic load in green cellular networks

Energy efficiency has become significantly important in designing future green mobile communication systems. In this paper, a novel energy efficiency metric, which is per energy per area capacity, is proposed to quantify the matching degree between energy consumption of Base Stations (BSs) and the traffic load. Based on BS power consumption model and Shannon capacity formula, the deployment strategies of different base station types are discussed, and the matching degree maximization is formulated as a convex optimization problem. The optimal cell size is proved to be the solution, which can be obtained by our presented iterative algorithm. Through theoretical inference and experimental simulations, we find that macro BS outperforms micro BS when the traffic density is pretty low, while it becomes reversed if the value exceeds the boundary. Besides, the heavier traffic demand results in a smaller optimal cell size.

A novel CAC-based network pricing scheme for wireless access networks

With the emergence of a large number of value-added services, radio resource become scarce, and they should be managed more efficiently to obtain the utility maximization. To achieve this object, we propose a novel network pricing scheme using CAC and NCC, in which the price is divided to service and congestion control cost. When the network is underlized, all the users are charged for service consumption. If congested, NCC is activated and all the users may make a decision due to congestion control cost and some of their resources will be occupied. By dynamically computing the prices for services at diverse time, our system can trade off between system performance and resources utilization.

Analysis of Queuing Behaviors with Self-similar Traffic in Wireless Channels

Many measurement studies showed that network traffic usually exhibits self-similar nature, meanwhile, wireless fading channels lead to the time-variant service rates of network nodes. Compared with classical queuing systems with Markov sources or constant service rates, the queuing system with self-similar input in a wireless fading channel is more complicated, and it is very difficult to obtain closed-form formulae for the queuing performances. In this paper, we study queuing behaviors with self-similar traffic input in wireless channels by establishing a queuing system model, and present a convenient and efficient algorithm to estimate the queue length distributions. Simulation results validate the accuracy of the proposed estimation algorithm. Finally, we analyze effective service rates of wireless channels based on the estimation algorithm, and draw some meaningful conclusions.

Study on service diffusion in Mobile Social Network

How to popularize the own Mobile Value-added Services (MVSs) in current mobile networks is interesting and important to many SP/CPs (Service Providers/Content Providers). In this paper, we focus on the study of service diffusion of MVSs and provide a novel methodology, which investigate that from a new perspective of epidemic spread. Firstly, we argue about the characteristics of Mobile Social Network (MSN), which is composed of mobile users, and analyze various factors that impact the subscribers to customize the MVSs. Then epidemic dynamics is used to depict the service diffusion and some conclusions including marketing strategy have been carried out thereinafter. Finally, through a series of experiments, we find that: 1) by using Acquaintance-First marketing strategy, the MVSs will quickly pop up at a low cost; 2) SP/CPs should do efforts to the effective spreading rate, which can result in a higher popularity of the service.

Service Model and NGN's New Service Deployment

The guiding principle of next generation network is separating service application layer and traffic transmission layer to build a network with characteristics of controllable, QoS guaranteed and service deployment open. But, what factors should be mainly thought about before new network service exploitation and deployment? This paper firstly proposed a service model including the characteristics of traffic generation and commerce revenue, named as Traffic-Charge Integrated Service Model (TCISM). Then, joining TCISM and three NGNs key parameters (network bound, resource price and QoS level), a basic methodology on NGNs service deployment process is given out to primarily answer the above question.

A novel communication service modeling

With forward to TCP/IP-based information network development, a large number of innovative communication services quickly emerged. In these data-based communications services, they require different communication rate and variable quality of service. And, the TCP/IP-based networks best-effort feature and statistical multiplexing strategy further makes the service capacity defined in telephone network no longer apply, when it is facing the new network and new communication services. To address the above problem, this paper introduces the difference between user-understanding information and machinery-understanding information, re-defines the communication service and proposes a service modeling. We hope to provide an objective and reasonable methods to evaluate the overall performance of the network and service, and guide the strategy management of the network and service to achieve the best balance between network efficiency and user experience.