In this paper, call admission and code allocation schemes are proposed to provide service differentiation in the forward link of wideband code-division multiple-access (WCDMA) systems. In particular, this paper proposes multiple leaf code reservation (MLCR) schemes, where different numbers of orthogonal variable spreading factor (OVSF) leaf codes (i.e., codes of the lowest layer of the OVSF code tree) are reserved to differentiate users with different bandwidth requirements. Leaf codes are only reserved for as long as the call admission process lasts. Once the decision of whether a new request is admitted or not has been made, a Code Dereservation procedure is carried out to increase flexibility in the code assignment phase. The performance of these MLCR strategies with/without code reassignments is then evaluated. Analysis shows that MLCR schemes are also useful in improving fair access among different traffic classes. In addition, perfect fair access among requests with different data rates can be achieved when code reassignments are jointly employed with the proposed OVSF-code reservation schemes.

In mobile cellular systems with link adaptation (LA), different quality/.ones, in terms of the Signal-to-interference Ratio (SIR), are distinguished. In this paper, the quality zone residence time distribution in mobile cellular systems with link adaptation is addressed. The cell residence time distribution has been widely studied in the literature. However, a literature survey shows that relatively few in-depth papers have addressed the quality zone residence time. In this work, comprehensive simulation results for a generalised mobility model are shown. Results show that as the mobility randomness increases, the probability density function of the quality zone residence time tends to a negative exponential one.