Gökhan Çelik

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IEEE 802.11 distributed coordination function, (DCF), provides contention-based distributed channel access for stations to share the wireless medium. However, Performance of IEEE 802.11 DCF protocol, in terms of delay and throughput, degrades dramatically as the number of active stations increases, especially when each station transmits in its saturated(More)
Development of a Medium Access Control (MAC) protocol that supports high throughput performance and quality of service (QoS) for real-time applications has become a major focus in WLAN research. IEEE 802.11 distributed coordination functions, (DCF/EDCA), provide contention-based distributed channel access for stations to share the wireless medium. However,(More)
Localization of the nodes in wireless networks is crucial for supporting the location-based services (LBSs). In this study, we investigate the fundamental limits for time delay based location estimation in amplify-and-forward (AF) cooperative relay networks considering multipath environment. The limits are presented by obtaining Cramer-Rao Lower Bounds(More)
Two patients with no symptoms of hypertension in their medical history before pregnancy were referred to the obstetrics emergency clinic with hypertension and visual complaints. After physical examination and laboratory tests, one of the patients was diagnosed with severe preeclampsia while the other was diagnosed with HELLP syndrome (Hemolysis-Elevated(More)
In this study, we investigate the fundamental limits for time delay based location estimation in decode-andforward (DF) relaying strategy based cooperative relay networks considering multipath environments. The limits are presented by obtaining Cramer-Rao Lower Bounds (CRLBs) expressions. Simulations are performed to verify the CRLB expressions and show the(More)
In this paper, we study the fundamental limits for time delay based location estimation in decode-and-forward (DF) cooperative relay networks. The Cramer-Rao Lower Bound (CRLB) expression for location estimation of source node in cooperative relay networks is derived under DF relaying strategy. The theoretical limits are investigated under different node(More)
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