Prioritized reservation type MAC protocol for broadband CDMA packet communication systems

Broadband CDMA packet access is one of the most promising air interfaces for future 4G mobile communication systems. In this study, a novel reservation-based access protocol with prioritized resource allocation (PRA) is proposed as a reverse channel MAC protocol, which enables various rate real-time communications on such a system. In this protocol, a low-rate temporal dedicated control channel (TDCCH) is momentarily assigned between a base station (BS) and mobile station (MS). A TDCCH is used to transmit not only access control signals including a reservation signal, but also transmission control signals such as transmission power control (TPC) commands. This protocol prevents a packet-by-packet setup delay and provides contention-free packet reservation so long as a TDCCH is established. The duration of the TDCCH can be controlled according to the quality of service (QoS) requirement. PRA is based on such a reservation scheme, and two different resource allocation areas are defined in time slots that correspond to real-time and best-effort classes. The real-time packets have a wider allocation area so that they can acquire radio resources prior to best-effort packets. Thus, resources are assigned to real-time packets first, and the remaining resources can be used for best-effort packet transmission. By combining admission control and flow control with PRA, real-time packet communication can be achieved in the reverse channel. The performance of the proposed protocol is evaluated by computer simulation and through an experimental system.