Mobility Aware Server Selection for Mobile Streaming Multimedia Content Distribution Networks

Abstract

We propose a Content Delivery Network (CDN) with servers arranged hierarchically in multiple tiers. Lower-tier servers are topologically closer to the clients, and hence can deliver better QoS in terms of end-to-end delay and jitter. On the other hand, higher-tier servers have a larger coverage area and hence their clients incur fewer server handoffs. We present a server selection scheme that reduces the number of server handoffs while meeting differentiated QoS requirement for each client. The scheme dynamically estimates the client’s residence time and uses a simple algorithm to assign clients to the appropriate tier. The scheme also caters for traditional server selection criteria, such as the expected QoS from the servers, bandwidth consumption, and the server load. We show through simulations that the scheme can achieve up to 15% reduction in handoffs, at the cost of minimal increases in delay and jitter while ensuring that clients of different QoS classes experience different delays.