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ABSTRACT: Spectrum sensing is a crucial measure for cognitive radio networks (CRN) to protect transmission of primary users. Cooperative spectrum sensing is regarded as the most promising method to improve the reliability of spectrum sensing. However, such cooperation also introduces overhead traffic of control signaling and result transmission which consumes more power in battery-operated mobile terminals. In this paper, an energy efficient transmission scheme is proposed. Clustering technique is adopted to save energy consumed in reporting results and exchanging information. All cognitive nodes are separated into a few clusters, and report local decisions to cluster heads to make cluster decisions through some data fusion method. Cluster decisions are forwarded to the common receiver to decide whether the spectrum of interest is idle or not. Simulation results demonstrate that the proposed method shows significant energy saving from 35% to 95% compared with the conventional scheme.
Wireless Communications, Networking and Mobile Computing, 2009. WiCom '09. 5th International Conference on; 10/2009
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ABSTRACT: To investigate the relationship between the successful results with different methods and time of initiation of respiratory support in critically ill patients.
The clinical data of 458 critical care patients were reviewed and analyzed. Among the patients, there were 47 cases of cardio-pulmonary resuscitation, 105 cases of acute airway obstruction, 156 cases of acute respiratory failure, and 150 cases of chronic respiratory failure. Intubation, or tracheostomy, or non-invasive positive pressure ventilation (NPPV) at different times and occasions were performed in the patients.
One hundred and seventeen cases (25.5%) died during the respiratory support treatment, 49 cases gave up the treatment, and 292 patients (63.8%) were cured after mechanical ventilation. As the success rate was the lowest in patients who survived cardio-pulmonary resuscitation (21.3%, 10/47), it was higher in acute respiratory failure (55.1%, 86/156), and the best result (82.8%, 87/105) was obtained in the acute airway obstruction group and patients with chronic respiratory failure (72.7%, 109/150). In the group of patients undergoing early respiratory support, the cure rate was 95.0% (57/60) in patients with invasive method, and 95.5% (21/22) in the NPPV group. The result was significantly different compared with that of later treatment group [81.7% (68/82) in invasive group, and 60.9% (2/29) in NPPV group, both P<0.01]. It demonstrated that the earlier the respiratory support was given the better results. If the respiratory support was delayed, cure rate was significantly reduced [65.6% (63/96) in invasive group and 48.1% (13/27) in NPPV group, both P<0.01]. The cure rate was no difference between different modes of respiratory support between early treatment groups, however, invasive respiratory support was much better than NPPV [44.4% (40/90) and 0 (0/5)] when instituted in the late stages (all P<0.01).
It is of prime importance to ensure optimal ventilation in the early stage of diseases, the difficulty and risk of establishment of a patent airway are main problems in the treatment of critically ill patients.
Zhongguo wei zhong bing ji jiu yi xue = Chinese critical care medicine = Zhongguo weizhongbing jijiuyixue 10/2009; 21(10):590-2.
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ABSTRACT: The fixed channelization structure used by IEEE 802.11-based WLANs constrains the total capacity and leads to unfairness. The concept of variable-width channels is recently proposed to overcome these drawbacks. To investigate the problem of the non-overlapping variable-width channel allocation for selfish access points (APs) in a WLAN, we model it as a non- cooperative game, we aim to investigate two fundamental issues on it in this paper: 1) Are there some fair and system-optimal Nash equilibrium (NE) allocations? 2) How to achieve one of these desirable allocations if they exist? At first, the existence of fair and system-optimal Nash equilibria in this game is proved. Then, a simple protocol to achieve one of these desirable NE allocations is proposed. Considering the implementation issues, a punishment-based method and a transfer-based self-enforcing truth-telling method are proposed for single-stage and multistage game scenarios respectively. The numerical results show the effectiveness of our approaches.
Communications, 2009. ICC '09. IEEE International Conference on; 07/2009
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Proceedings of the 2009 ACM Workshop on Cognitive Radio Networks, CoRoNet 2009, Beijing, China, September 21, 2009; 01/2009
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01/2009
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01/2009
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7th Annual Conference on Communication Networks and Services Research, CNSR 2009, 11-13 May 2009, Moncton, Canada; 01/2009
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Proceedings of the 69th IEEE Vehicular Technology Conference, VTC Spring 2009, 26-29 April 2009, Hilton Diagonal Mar, Barcelona, Spain; 01/2009
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Proceedings of the Global Communications Conference, 2008. GLOBECOM 2008, New Orleans, LA, USA, 30 November - 4 December 2008; 01/2008
