Packet scheduling in third-generation mobile systems with UTRA-TDD air interface

UTRA-TDD is one of the adopted air interfaces for third-generation mobile communication systems (UMTS). In UTRA-TDD, information packets are transmitted organized into radio frames. A radio frame is divided into a fixed number of time slots and different packets can be sent on the same time slot by means of the Code Division Multiple Access technique. Packets belong to different traffic classes and have different formats and Quality of Service (QoS) requirements in terms of delay, transmission error probability and priority level. In this paper, we address the problem of scheduling packets for downlink transmissions in the time slots of a frame, in such a way that QoS requirements are fulfilled. In particular, exact pseudo-polynomial and heuristic scheduling algorithms are compared in terms of typical performance parameters. Computational results for three traffic classes show that the proposed algorithms are suitable for UTRA-TDD implementation, both for solution quality and computational time.