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Link-Level Performance of Cooperative Multi-Hop Relaying Networks with MDS Codes
Sakakibara, Katsumi,Ito, Daichi,Taketsugu, Jumpei The Korea Institute of Information and Commucation 2011 Journal of communications and networks Vol.13 No.4
We evaluate the link-level performance of cooperative multi-hop relaying networks with an maximum distance separable (MDS) code. The effect of the code on the link-level performance at the destination is investigated in terms of the outage probability and the spectral efficiency. Assuming a simple topology, we construct an absorbing Markov chain. Numerical results indicate that significant improvement can be achieved by incorporating an MDS code. MDS codes successfully facilitate recovery of the message block at a relaying node due to powerful error-correcting capability, so that it can reduce the outage probability. Furthermore, we evaluate the average number of hops where the message block can be delivered.
Sakakibara, Katsumi,Taketsugu, Jumpei The Korea Institute of Information and Commucation 2010 Journal of communications and networks Vol.12 No.1
IEEE 802.11 defines distributed coordination function (DCF), which is characterized by CSMA/CA and binary exponential backoff (BEB) algorithm. Most modifications on DCF so far have focused on updating of the contention window (CW) size depending on the outcome of own frame transmission without considering freezing periods experienced in the backoff interval. We propose two simple but novel schemes which effectively utilize the number of freezing periods sensed during the current backoff interval. The proposed schemes can be applied to DCF and its family, such as double increment double decrement (DIDD). Saturation throughput of the proposed schemes is analyzed by means of Bianchi's Markovian model. Computer simulation validates the accuracy of the analysis. Numerical results based on IEEE 802.11b show that up to about 20% improvement of saturation throughput can be achieved by combining the proposed scheme with conventional schemes when applied to the basic access procedure.
Sakakibara Fumihiro,Uchida Kazutaka,Yoshimura Shinichi,Sakai Nobuyuki,Yamagami Hiroshi,Toyoda Kazunori,Matsumaru Yuji,Matsumoto Yasushi,Kimura Kazumi,Ishikura Reiichi,Inoue Manabu,Ando Kumiko,Yoshida 대한뇌졸중학회 2023 Journal of stroke Vol.25 No.3
Background and Purpose Differences in measurement of the extent of acute ischemic stroke using the Alberta Stroke Program Early Computed Tomographic Score (ASPECTS) by non-contrast computed tomography (CT-ASPECTS stratum) and diffusion-weighted imaging (DWI-ASPECTS stratum) may impact the efficacy of endovascular therapy (EVT) in patients with a large ischemic core. Methods The RESCUE-Japan LIMIT (Recovery by Endovascular Salvage for Cerebral Ultra-acute Embolism Japan–Large IscheMIc core Trial) was a multicenter, open-label, randomized clinical trial that evaluated the efficacy and safety of EVT in patients with ASPECTS of 3–5. CT-ASPECTS was prioritized when both CT-ASPECTS and DWI-ASPECTS were measured. The effects of EVT on the modified Rankin Scale (mRS) score at 90 days were assessed separately for each stratum. Results Among 183 patients, 112 (EVT group, 53; No-EVT group, 59) were in the CT-ASPECTS stratum and 71 (EVT group, 40; No-EVT group, 31) in the DWI-ASPECTS stratum. The common odds ratio (OR) (95% confidence interval) of the EVT group for one scale shift of the mRS score toward 0 was 1.29 (0.65–2.54) compared to the No-EVT group in CT-ASPECTS stratum, and 6.15 (2.46–16.3) in DWI-ASPECTS stratum with significant interaction between treatment assignment and mode of imaging study (<i>P</i>=0.002). There were significant interactions in the improvement of the National Institutes of Health Stroke Scale score at 48 hours (CT-ASPECTS stratum: OR, 1.95; DWIASPECTS stratum: OR, 14.5; interaction <i>P</i>=0.035) and mortality at 90 days (CT-ASPECTS stratum: OR, 2.07; DWI-ASPECTS stratum: OR, 0.23; interaction <i>P</i>=0.008). Conclusion Patients with ASPECTS of 3–5 on MRI benefitted more from EVT than those with ASPECTS of 3–5 on CT.
Link-Level Performance of Cooperative Multi-Hop Relaying Networks with MDS Codes
Katsumi Sakakibara,Daichi Ito,Jumpei Taketsugu 한국통신학회 2011 Journal of communications and networks Vol.13 No.4
We evaluate the link-level performance of cooperative multi-hop relaying networks with an maximum distance separable (MDS) code. The effect of the code on the link-level performance at the destination is investigated in terms of the outage probability and the spectral efficiency. Assuming a simple topology, we con-struct an absorbing Markov chain. Numerical results indicate that significant improvement can be achieved by incorporating an MDS code. MDS codes successfully facilitate recovery of the message block at a relaying node due to powerful error-correcting capabil-ity, so that it can reduce the outage probability. Furthermore, we evaluate the average number of hops where the message block can be delivered.