On RACH preambles separation between human and machine type communication

In LTE and LTE-Advanced systems the rate of requests on the Random Access CHannel (RACH) can be high. Indeed, the Machine Type Communication (MTC) implies to have a high number of devices that need to request radio resources for transmitting small amount of data. Furthermore, reducing the time in which radio resources are allocated to Human Type Communications (HTC) for energy savings purposes, may lead to radio access network overload as well. In this framework, this paper aims at providing a set of guidelines for the resource allocation task in the RACH. In particular, the study investigates the impact of both the backoff indicator scheme and the maximum number of retransmissions on the RACH performance parameters. The rate of RACH requests associated with the HTC traffic is modelled by inferring their statistical properties starting from a dataset acquired in an operational eNodeB. The estimation of the average delay and the average number of maximum retransmissions gives insights on how many preambles should be reserved for HTC in order to meet the target performance, and provides suggestions on the configuration of the backoff indicator.