This paper proposes an adaptive transmission scheme for MIMO systems to provide different bit error rates and transmission rates for multimedia traffic. The adaptive transmission scheme allocates antennas, rate and power jointly according to the feedback information to satisfy the diverse QoS requirements of the multimedia traffic. Furthermore, an efficient search algorithm with low complexity is proposed for practical implementation. Simulation results show that the proposed scheme improves the spectral efficiency while guaranteeing the QoS requirements of multimedia traffic. Moreover, the proposed search algorithm achieves close optimal performance with great complexity reduction.

Radio resource is the bottleneck for current multimedia wireless networks. Intelligent traffic control strategies can be enforced to optimize resource allocation so as to enhance network performance. In this study, dynamic control scheme for non-real-time traffic and autonomic control schemes for multimedia traffic are proposed to guarantee the required quality of service (QoS) in the inference-dominated high-speed wireless environment. Both handoff priority and terminal mobility are also taken into consideration. The performance of the state-dependent multidimensional birth-death process is derived by the efficient matrix-analytic methods (MAMs). Compared with the previous results, this paper shows that the proposed control methods can be used for both real-time and non-real-time multimedia traffic in order to meet the required performance without degrading the quality of multimedia services. These results are also important for the design of evolving multimedia wireless systems as well as network optimization.

In this article we analyze the performance of a space division output buffered multichannel switch operating in an ATM multimedia environment as follows. Fixed size packets belonging to two classes arrive onto the switch inputs in each time slot. Class-1 packets, representing real time traffic such as live audio and live video communications, are sensitive to delay but insensitive to loss and have their own service time needs. Class-2 packets, representing nonreal time communications such as file transfers, are insensitive to delay but sensitive to loss and have their different service time needs. To respond to the class-1 delay sensitivity, the switch gives class-1 packets higher service priority over class-2. And to respond to the difference in service time needs, the switch operates at two service rates, one for each class. This latter assumption is the major feature of the article, as previous studies have usually assumed that the two classes have the same service needs and thus the same service rate. For the purpose of the analysis, the switch is modelled as a priority, discrete time, batch arrival, multiserver queueing system, with infinite buffer and two geometric service times with two parameters. Performance measures analyzed are system occupancy and packet waiting time.

A key problem under imperfect power control in multimedia DS-CDMA networks is how to guarantee the differentiated outage probabilities of different traffic classes resulted from the uncertainty of received powers. In addition, in order to utilize the scarce wireless resource efficiently, as many users as possible should be admitted into the network while providing guaranteed quality-of-service support for them. In this work, a call admission control scheme, Differentiated Outage Probabilities CAC or DOP-CAC, is proposed to achieve the above goals for imperfectly power-controlled multimedia CDMA networks. Two important features of CDMA systems are considered in our scheme: one is the power multiplexing among bursty traffics and the other is the power allocation scheme employed at the physical layer. The validity and efficiency of DOP-CAC are verified by numerical examples. Two power allocation schemes, Limited Optimal Power Allocation (LOPA) proposed in [3] and Quasi-Optimal Power Allocation (QOPA) we proposed in [6], are considered respectively and compared in the performance evaluation of DOP-CAC. The results show that DOP-CAC achieves much better resource utilization under QOPA than it does under LOPA. By employing QOPA at the physical layer and DOP-CAC at the link layer, our work suggests a high efficiency solution for QoS support of multimedia traffic under imperfect power control environment.

In this paper, we propose a medium access control (MAC) protocol for multimedia code division multiple access (CDMA) communications. In the proposed protocol, a base station (BS) estimates the instantaneous number of simultaneously transmitted packets in the future slots with exploiting a stochastic property of traffic. In order to carry out this estimation, we employ an adaptive algorithm. We evaluate the performance of the proposed protocol by comparing that with two different cases. One is no estimation case and the other is perfect estimation case. From these results, we clarify the advantage of the proposed MAC protocol.

Future wireless communication systems will provide mobile terminals with high bit-rate transmissions for accessing broadband wired networks. In this paper, we envisage a Time Division Multiple Access - Time Division Duplexing (TDMA-TDD) air interface and we propose a Medium Access Control (MAC) protocol, named Dynamic Scheduling - TDD (DS-TDD), that allows guaranteeing the QoS of different traffic classes and efficiently supports uplink/downlink traffic asymmetries. The DS-TDD performance is theoretically analyzed. Moreover, the DS-TDD protocol is compared with another scheme proposed in the literature. Finally, the impact of packet errors on the DS-TDD performance is evaluated.

The reverse link signal power required for multimedia traffic in multipath faded single-code (SC-) and multi-code CDMA (MC-CDMA) systems is investigated. The effect of orthogonality loss among multiple spreading code channels is characterized by introducing the orthogonality factor. The required signal power in both CDMA systems is analyzed with varying system parameters of spreading bandwidth, the orthogonality factor, and the number of spreading codes. Analytical results show that MC-CDMA users transmitting only a single traffic type require significantly more power than SC-CDMA users with only a single traffic type. On the other hand, MC-CDMA users transmitting multimedia traffic require power levels approximately identical to SC-CDMA users with multimedia traffic.