Abstract

Wireless networks have focused on voice call services or wireless Internet access services. These days, the application service domain of wireless networks is rapidly expanding, and a wide variety of new services is emerging. Video streaming service is one of the most promising examples, evidenced by 3GPP’s MBMS (Multimedia Broadcast Multicast Service) and IMS (IP Multimedia Subsystem). In this paper, we consider the provision of video streaming services in hierarchical wireless networks with multiple layers of cells. We particularly focus on optimal load balancing among the cells, aiming at the minimization of frame drop ratio for given video streaming sessions. From this objective function, we derive the optimal load balancing condition. Load balancing is essentially the issue of which users are assigned to which cell, i.e., the user assignment problem. In our user assignment algorithm, we compute thresholds to divide users into groups according to the user characteristics, and map the user groups to proper cells. The optimal load balancing condition can be reached by adaptively adjusting the threshold at run time. This process does not require prior knowledge about the system status, such as the system capacity or user traffic requests, which warrants the practicality of the proposed scheme. Via simulations, we demonstrate that the proposed scheme achieves optimal load balancing in various realistic environments.

Keywords: Optimal load balancing; Assignment strategy; Hierarchical wireless networks; Video streaming services

Article Outline

1. Introduction

2. System model

2.1. Application model

2.2. Assignment strategy

2.3. Network model and user dynamics

3. Optimal load balancing scheme

3.1. Objective function

3.2. Optimal threshold

3.3. Adaptive threshold adjustment

4. Simulation results

4.1. Simulation setup

4.2. Accuracy of theoretical analysis

4.3. Finding optimal threshold

4.4. Frame drop ratio minimization

5. Conclusion

Appendix. Summary of notations

References

Vitae