A packet age based LTE uplink packet scheduler for M2M traffic

M2M applications exhibit a wide variety of QoS requirements, but many, particularly those associated with monitoring and/or control, are delay sensitive and therefore have specific packet delay budgets. One of the issues when supporting such delay sensitive M2M applications over a wide area cellular standard such as LTE is that the base station scheduling entity cannot precisely ascertain when pending uplink packets at devices were generated. This makes scheduling according to deadlines based upon packet delay budgets very challenging and ultimately involves some degree of error. In this paper, we propose a new delay sensitive scheduler that increases the probability of satisfying the delay budget of packets by exploiting Packet Age (PA) data explicitly reported by devices. The PA is a new MAC Control Element that represents the age of the oldest pending packet in the device buffers and is sent by devices in parallel with the existing Buffer Status Report (BSR) that contains volume and priority data. The overhead associated with the PA MAC control element is extremely small (2 bytes). We demonstrate the performance of the new technique with an OPNET simulation of an LTE TDD system serving event driven delay sensitive M2M traffic, comparing the results when PA reporting is enabled versus disabled for essentially the same uplink scheduling algorithm.