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— In this paper, we propose an analytical Markov Chain model of the slotted CSMA/CA protocol for IEEE 802.15.4 under unsaturated traffic conditions. Our proposed Markov Chain model reflects the characteristics of the IEEE 802.15.4 MAC protocol, such as a superframe structure, acknowledgements , and retransmissions with and without limit. We evaluate the(More)
—In this paper, we consider a time slotted cognitive radio network where multiple secondary users (SUs) contend to access wireless channels. We propose and analyze a channel access policy where each secondary user stochastically determines whether to access a wireless channel (or not) based on a given access probability. In our analysis we consider two(More)
— In this paper, we propose a useful framework for the cross-layer design and analysis of wireless networks where ARQ (Automatic Repeat reQuest) and AMC (Adap-tive Modulation and Coding) schemes are employed. To capture the joint effect of the packet transmission error rate at the PHY layer and the packet loss probability at the MAC layer, we introduce the(More)
— In this paper, we focus on a packet scheduling algorithm exploiting multiuser diversity in wireless networks. We compare the delay performance of individual user under the scheduling algorithm exploiting multiuser diversity with that under the round-robin scheduling algorithm in order to reveal the characteristics of the scheduling algorithm exploiting(More)
SUMMARY As the IEEE 802.16e Wireless Metropolitan Access Network (WMAN) supports the mobility of a mobile station (MS), increasing MS power efficiency has become an important issue. In this paper, we analyze the sleep-mode operation for an efficient power saving mechanism for delay-guaranteed services in the IEEE 802.16e WMAN and observe the effects of the(More)
— In this letter, we propose a new downlink fair scheduling scheme exploiting the multiuser diversity to enhance the transmission capacity. In the proposed scheme, only the MSs (mobile stations) whose normalized SNR (signal-to-noise ratio) values are larger than a given threshold feed back one-bit information to the BS (base station). As a result, while(More)
—To mathematically model the Rayleigh fading channel , we propose a new method to partition the received Signal-to-Noise ratio (SNR) range into a finite number of states and construct a finite state Markov chain (FSMC). Our method is based on the assumption that the transitions of the FSMC occur only between adjacent states. We provide numerical and(More)
We analyze a multi-server priority queueing system with partial buffer sharing, where the input is a discrete autoregressive process of order 1 (DAR(1)) which is known as a good mathematical model for a VBR-coded teleconference video traffic. We assume that arriving packets are classified into two priority classes, say, high priority class and low priority(More)