Measurement-adaptive cellular random access protocols

This work considers a single-cell random access channel (RACH) in cellular wireless networks. Communications over RACH take place when users try to connect to a base station during a handover or when establishing a new connection. We approach the problem of optimal coordination of user actions, taking into account a dynamic environment (channel fading, mobility, etc.). Within the framework of Self-Organizing Networks (SONs), the system should self-adapt to such environments without human intervention. To do so certain information should be gathered at the base station. For the performance improvement of the RACH procedure, we propose protocols which exploit information from measurements and user reports in order to estimate current values of the system unknowns and broadcast global action-related values to all users. The protocols suggest an optimal pair of user actions (transmission power and back-off probability) found by minimizing the drift of a certain function. Numerical results illustrate the great performance benefits at a very low or even zero cost in power expenditure and delay, as well as the fast adaptability of the protocols to envoronment changes.