Abstract-Resource allocation and call admission control (CAC) are key management functions in future cellular networks, in order to provide multimedia applications to mobiles users with quality of service (QoS) guarantees and efficient resource utilization. In this paper, we propose and analyze a priority based resource sharing scheme for voice/data integrated cellular networks. The unique features of the proposed scheme are that 1) the maximum resource utilization can be achieved, since all the leftover capacity after serving the high priority voice traffic can be utilized by the data traffic; 2) a Markovian model for the proposed scheme is established, which takes account of the complex interaction of voice and data traffic sharing the total resources; 3) optimal CAC parameters for both voice and data calls are determined, from the perspective of minimizing resource requirement and maximizing new call admission rate, respectively; 4) load adaption and bandwidth allocation adjustment policies are proposed for adaptive CAC to cope with traffic load variations in a wireless mobile environment. Numerical results demonstrate that the proposed CAC scheme is able to simultaneously provide satisfactory QoS to both voice and data users and maintain a relatively high resource utilization in a dynamic traffic load environment. The recent measurement-based modeling shows that the Internet data file size follows a lognormal distribution, instead of the exponential distribution used in our analysis. We use computer simulations to demonstrate that the impact of the lognormal distribution can be compensated for by conservatively applying the Markovian analysis results.Index Terms-Call admission control (CAC), quality-of-service (QoS), resource allocation, voice and data services.

No abstract

Call admission control (CAC) in future wireless personal communication systems is to simultaneously achieve quality-of-service satisfaction and high resource utilization. It poses significant technical challenges due to scarce radio spectrum, user mobility, hostile wireless propagation environment, end-to-end connectivity, and dynamic nature of multimedia traffic. This paper aims at providing a survey on the existing literature related to the works on CAC for future wireless systems, especially in the wireless and combined wireless/wireline domains. As the concepts of the virtual connection tree (VCT) and cell cluster have been proposed to handle user mobility, both centralized CAC policies for systems using static VCT static cell cluster and distributed CAC policies for systems using dynamic VCT dynamic cell cluster are discussed. Comparisons among the various CAC solutions are made, problems that have been dealt with and problems that need to be tackled are identified for perspective researchers in this area.

Call admission control (CAC) in multimedia wireless communications is to guarantee quality of service (QoS) to mobile users and to achieve a high resource utilization ef®ciency. It is a challenging issue due to user mobility, limited radio spectrum, heterogeneous nature of multimedia traf®c. This paper proposes a CAC policy for a wireless system supporting both constant-rate voice calls and available-rate data calls. The parameters of the proposed policy is determined in a systematic way by using an optimization approach. Soft QoS (relaxed target QoS) is introduced to make a compromise between the QoS levels of the voice and data calls, respectively, in a heavy traf®c load situation. Numerical results show that the proposed CAC policy can guarantee the QoS of all the users under most traf®c conditions considered.

A Chinese medicinal formulation, 'Liu Wei Di Huang', and its individual components have been tested for the genoprotective effect on human DNA by the comet assay. Results showed no DNA protection contributed by this prescription. However, the aqueous extracts of individual herbs, namely Cortex Moutan and Rhizoma Dioscoreae, were able to decrease by 10-15% the DNA stand break from hydrogen peroxide-mediated oxidative stress. This provides insight to further evaluate the interaction among herbs and the search for the active ingredient responsible for the DNA protective effect.