We propose access control protocols based on a prediction of the residual capacity available for data users. These protocols provide constant-bit-rate (voice), variable bit rate (video), and low priority data services in integrated voice/data/video code division multiple access (CDMA) systems. Three different access control protocols such as scheduled access of constant bit rate (CBR) data users, random access of CBR data users, and scheduled access of variable bit rate (VBR) data users are compared.

CPCH (common packet channel) is an uplink common channel made by 3GPP to support rather a reliable packet transport. In this paper, we propose a new access scheme to provide a prioritized service. Discrimination of the backoff timer is applied and the channel characteristic is described. We also present a simple system model of CPCH for EPA and use it to get a mathematical result. The results show that the multi-class service with different priorities can be, effectively and easily, served by the proposed scheme.

We propose a direct-sequence spread spectrum multiple access (DS/SSMA) unslotted ALOHA system with two user classes and analyze the throughput of the proposed system. Mobile stations (MSs) are divided into two classes according to payment or traffic characteristics, such as delay-intolerant and delay-tolerant. Different permission probabilities are assigned to each class so that the appropriate quality of service can be provided. We assume that the generation of class 1 and 2 messages are Poisson distributed and the message is divided into several packets before transmission. The system is modeled as a two-dimensional Markov chain under the assumption that the number of packets transmitted immediately by both user classes is geometrically distributed and the packet length is constant. We calculate the packet success probability and the throughput as a function of the signal-to-noise ratio (SNR) during packet transmission, considering the number of overlapped class 1 and 2 messages and the amount of their time overlap. Moreover, we show that the proposed system differentiates user packets according to class and maintains a high throughput even under heavy traffic conditions using access control based on the channel load.

We analyze the throughput of a direct-sequence spread spectrum multiple access (DS/SSMA) unslotted ALOHA system with variable length data traffic. The system is analyzed for two cases: (1) systems without a channel load sensing protocol (CLSP) and (2) systems with a CLSP. The bit-error probability and the throughput are obtained as a function of the signal-to-noise ratio (SNR) during message transmission, considering the number of overlapped messages and the amount of time overlap. We assume that the generation of data messages is Poisson distributed and that the messages are divided into packets before transmission. The system is modeled as a Markov chain under the assumption that the number of packets in a message is geometrically distributed with a constant packet length. The throughput variance of the DS/SSMA unslotted ALOHA system with variable length data traffic is obtained as the Reed-Solomon code rate varies. Results show that a significant throughput improvement can be obtained by using an error-correcting code.

The cdma2000, a candidate submission to ITU-R for IMT-2000 radio interface, has many MAC states such as control hold state (CHS), active state (AS), suspended state (SS), and dormant state (DS) for packet data services. A mobile station consumes the power differently as these MAC states and many timer objects called normal hold timer, slotted hold timer, virtual traffic timer, and slotted suspended timer, determine the MAC transition time of packet data. We show the relationship between the achieved power saving gain and the mean packet delay degradation.