Adaptive multicore scheduling for the LTE uplink

Abstract

The Long Term Evolution (LTE) is the next generation cellular system of 3GPP, where every subframe (1 millisecond duration), a base station receives information from up to one hundred users. Multicore heterogeneous embedded systems with Digital Signal Processors (DSP) and coprocessors are power efficient solutions which decode the LTE uplink signals and encode the downlink LTE signals in base stations. The LTE Physical Uplink Shared Channel (PUSCH) uses a dynamic algorithm, as its multicore scheduling must be adapted every subframe to the number of transmitting users and to the data rate of the services they require. To solve this particular issue of the dynamic deployment while maintaining low latency, one approach is to find efficient on-the-fly solutions using techniques such as graph generation and scheduling. This approach is opposed to a fully static scheduling of predefined cases, approach currently used in the UMTS deployments. We show that the fully static approach is not suitable for the LTE PUSCH and that present DSP cores are powerful enough to recompute an efficient adaptive schedule for the application most complex cases in real-time.