Time-Division-Based Cyclic Scheduling for UMTS High-Speed Downlink Shared-Channels

Abstract

Third Generation Partnership Project working group proposes the high-speed downlink packet access to speed up downlink transmission for the universal mobile telecommunication system, where the time-division-based high-speed downlink shared-channel (HS-DSCH) approach is adopted. Our previous work proposed the shared-channel assignment and scheduling (SCAS) scheme to efficiently schedule the DSCH to serve different connections, which guarantees the requested transmission rate for each connection. However, limitations exist in the SCAS scheme: 1) the requested transmission rates of connections must be two's power numbers of the basic transmission rate and 2) all served connections should be rescheduled while a new request is granted, which introduces extra rescheduling overhead to the system. This paper proposes the elastic shared-channel assignment and scheduling (eSCAS) scheme to overcome these limitations. We formally prove the correctness of the eSCAS scheme. An analytical model and simulation experiments are conducted to compare the performance for eSCAS and SCAS. Our study shows that eSCAS can significantly improve the acceptance rate for new connections without increasing the rescheduling overhead.Index Terms-High-speed downlink packet access (HSDPA), high-speed downlink shared-channel (HS-DSCH), orthogonal variable spreading factor (OVSF), scheduling, universal mobile telecommunication system (UMTS).

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“…Therefore, we assume t 1 to be Gamma distributed (note that the Gamma distribution is a generalization of the Erlang distribution). The Gamma distribution is also widely used in telecommunications modeling [10], [11], [12] because it has been shown that the distribution of any positive random variable can be approximated by a mixture of Gamma distributions (see Lemma 3.9 in [13]). We can measure the signaling delays from the field operations and then generate the Gamma/Erlang distributions from the measured data.…”