Joint packet- and call-level soft handoff in CDMA wireless cellular networks

Soft handoff and call admission control (CAC) in a packet switching CDMA wireless cellular system are studied. A normal cell area is divided into an inner cell area and a handoff area, based on which a cell capacity vector and a call admission region are derived for uplink transmission to satisfy user quality of service (QoS) requirements and to minimize the grade of service (GoS) function. The QoS parameters under consideration arc the transmission bit error rate (BER) and packet loss rate (PLR). The BER requirement is guaranteed by properly arranging simultaneous packet transmissions, whereas the PLR requirement is satisfied by proper packet scheduling for calls in the inner cell and handoff areas. The GoS function is minimized by considering both new call blocking and handoff call dropping probabilities. By taking traffic characteristics and dynamic scheduling of nonhandoff and handoff calls into account, the proposed packet scheduling scheme achieves fair packet transmissions and greatly enlarges the call admission region.