LTE Advanced: 3GPP Solution for IMT-Advanced

8.3 Traffic Steering and Mobility Management

Traffic steering allows operators to optimize resource utilization, users' service perception and terminal or base station power consumption by directing the traffic to the RAT or layer that provides the best performance regarding any metric of interest. However, this has to be tied closely together with mobility management, which assures robust and optimized mobility performance, for example a reasonable number of handovers and avoidance of radio link failures and ping-pongs.

Especially in the context of heterogeneous networks, traffic steering is a major driver of operational expenses (OPEX) reduction and it enables the limiting or postponement of capital expenses (CAPEX). A common strategy in this respect is to offload as much traffic as possible to femto or WiFi cells, since these typically involve an inexpensive backhaul infrastructure. Furthermore, load balancing between the remaining layers and RATs allows using base station infrastructure more efficiently, hence improving return on investment, and offering a more homogeneous quality of service. Traffic steering needs to take into consideration factors such as:

• signal strength and interference;
• terminal and network capabilities;
• requested services and quality of service (QoS);
• load in different RATs and layers;
• power consumption on the base station and terminal side; and
• terminal speed.

LTE and LTE-Advanced provide various means to perform traffic steering, which are typically ...