In integrated voice/data cellular mobile networks, the most important consideration is to utilize the resources in an efficient way and maintain the required quality of service (QoS). In this paper, we proposed a new call admission control scheme for improving efficiency of resource utilization. Proposed scheme restricts the new and handoff voice and data calls arrived to system by finding the optimal threshold number of new and handoff voice and data calls allowed in system according to admission criters such as maximum data response time, voice and data blocking and dropping probabilities. From the numerical analysis, we observed that required call-level QoS for both voice and data calls is provided and upper bound of data response time is guaranteed to data calls. Also taking the required minimum bandwith need of voice calls in different values, we evaluated the performance improvements of data calls.

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Supporting real-time communications over IEEE 802.11 wireless local area networks (WLANs) is very important yet challenging due to the limited channel capacity, unstable channel conditions, and the low transmission delay requirement of real-time traffic. In this paper, we propose a new analytical model to improve the delay and throughput performance of the real-time applications over WLANs. We model each node as an M/G/1/K queue and the random access process as a two-dimensional Markov chain. Taking into account the rate adaptation feature of real-time applications, we design an iterative searching algorithm to look for the optimal number of retransmission m in the MAC layer with concurrent exploration of the Markov chain and the M/G/1/K queuing models and the variation of the arrival rate. Performance results demonstrate that our analytical model can effectively improve the throughput and average delay under different conditions studied.

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Vehicle-to-infrastructure and vehicle-to-vehicle communications has been introduced to provide high rate Internet connectivity to vehicles to meet the ubiquitous coverage and increasing high-data rate internet and multimedia demands by utilizing the 802.11 access points (APs). In order to evaluate the performance of vehicular networks over WLAN, in this paper, we investigate the transmisison and network performance of vehicles that pass through AP by considering contention nature of vehicles over 802.11 WLANs. Firstly, we derived an analytical traffic model to obtain the number of vehicles under transmision range of an AP. Then, incorporating vehicle traffic model with Markov chain model and for arrival packets, M/G/1/K queuing system, we developed a model evaluating the performance of DCF mechanism with an optimal retransmission number. We also derived the probability of mean arrival rate l to AP. A distinctive aspect of our proposed model is that it incorporates both vehicular traffic model and backoff procedure with M/G/1/K queuing model to investigate the impact of various traffic load conditions and system parameters on the vehicular network system. Based on our model, we show that the delay and througput performance of the system reduces with the increasing vehicle velocity due to optimal retransmision number m, which is adaptively adjusted in the network with vehicle mobility.

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ÖzetçeBu çalÕúmada, çoklu-servis kablosuz hücresel a÷larda ses ve veri servisleri için etkili kaynak yönetim tekniklerinden olan arama izin úemalarÕ (Call Admission Control, CAC) incelenmiú ve tamamen-bölüúümlü (CP, Complete-Partitioning) paylaúÕm tekni÷i üzerinden verinin de÷iúebilir band geniúli÷i tahsisine izin veren yapÕsÕ kullanÕlarak yeni bir arama izin úemasÕ önerilmiútir. Ses aramalarÕ gerçek-zamanlÕ ve sabit band geniúli÷i gerektiren, veri aramalarÕ ise gerçek-zamanlÕ olmayan ve servis kalitesinden ödün vermeden mümkün olabilecek de÷iúebilir band geniúliklerinde çalÕúabilen servislerdir. Veri aramalarÕnÕn bu özelli÷i ile durum-ba÷ÕmlÕ (state-dependent) servis oranlarÕ elde edilmiútir. øzin úemasÕnÕn performansÕnÕ ölçebilmek için ikiboyutlu Markov Zinciri modellenmiú, matematiksel olarak bu model üzerinden performans ölçütleri ses ve veri aramalarÕnÕn bloklanma/ düúürülme olasÕlÕklarÕ, her bir durum (state) için hesaplanmÕútÕr. SayÕsal sonuçlar önerilen úemanÕn kaynak kullanÕmÕnda hedeflenen QoS (Quality of Servis) parametre de÷erlerini sa÷ladÕ÷ÕnÕ göstermiútir. Abstract In this work, Call Admission Control Schemes which is one of the efficient resource management techniques are analyzed and proposed a new call admission scheme by using the structure of data allowing available bandwidth allocation over Complete-Partitioning Sharing technique. Voice calls are real-time services and needs fixed bandwidth, on the other hand, data calls are non-real time services and adaptable to work in available bandwidth without a concession made for Quest. It is obtained state-dependent service rates by means of this structure of data and modeled two-dimensional(2-D) Markov Chain to be able to measure performance of the proposed scheme and calculated mathematically performance measurements that is voice/data blocking/dropping probabilities for each state over this model Numerical results show that proposed scheme guaranteed the targeted QoS parameters levels in resource utilization. SIU2010 -IEEE 18.Sinyal isleme ve iletisim uygulamalari kurultayi -Diyarbakir 978-1-4244-9671-6/10/$26.00 ©2010 IEEE

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