Search

Researchers investigated the testing and evaluation of radio and communication protocol standards for the 5.9 GHz spectrum that has been approved by the Federal Communications Commission for exclusive transportation use. This spectrum allocation is intended for use as Dedicated Short Range Communications (DSRC) in the context of high-value Intelligent Transportation Systems (ITS) applications. In this report, we summarize the Wireless Access in a Vehicular Environment (WAVE) standardization effort for 5.9 GHz DSRC, its current status, and related issues of the IEEE 802.11p and IEEE 1609 family of standards. We also present an overview of current DSRC development activities in the world context, in the United States, and in California, describing and comparing some of the current commercial implementations. To verify the performance of DSRC prototype radios, we conducted a series of testing in different scenarios. A physical layer simulation and FPGA testbed was developed at the UnWiReD Lab, University of California, Los Angeles, and a software applications programming interface (API) used in tests with different commercial hardware was developed at California PATH, UC Berkeley. The WAVE standards effort, in which we participated, is described, and testing procedures and results are presented. An architecture for DSRC testbeds for safe intersections is reported, focusing on the hardware/software issues, performance and possible future enhancements. Finally, a user‘s guide to our developed software for testing DSRC/WAVE systems is provided as an appendix.

This PATH Research Report covers the (Vehicle-Infrastructure Integration) VII California Development and Deployment (Task Order 5217) efforts from October 2005 – December 2007. Because TO 5217 is followed by the continuation TO 6127, it is a compendium of very applications-oriented research to date as well as a final report to TO 5217.It is organized to impart the very specific and generally very pragmatic implementation details first, beginning with an introduction (Section 1), description of VII hardware, general network and installation (Section 2), then progressing to a more detailed description of the network and operating software (Section 3) and finally to applications in development and prospective applications (Section 4). Because it is not yet a final report but rather a ‘research in progress’ report, it does not comprehensively address every task in the VII California family of task orders; specifically, several of the applications described in Section 4 are represented as works in progress (as they are at this writing), and the on-ramp metering study is not yet reported. Again, the purpose, of this report is to provide the reader with an understanding of how VII California was implemented.

This report investigates the performance of model-based estima-tion over multi-access networks and emphasizes on the estimationMSE (mean squared error) while using different channel access schemes:probabilistic (random access), deterministic (round-robin scheduling),and combined (grouped channel access). We propose a mathematicalframework for estimation over a simple multi-access MAC protocol,the slotted ALOHA network. Estimation MSE, its asymptotic be-havior and stability condition are derived for different channel accessmethods. Our quantitative discussion can provide guidelines to designthe communication logic for those vehicular control systems built ontop of multi-access networks.

Background: Epistaxis is a common disease. That is usually self-limited and controlled by extemal compression. However, posterior epistaxis is occasionally complicated and needs hospitalization. The aim of this study is to analyze the etiology of epistaxis that requires hospitalization, and present the results of the treatments., Methods: From June 1997 to May 1999, 44 patients admitted under diagnosis of epistaxis were retrospectively investigated. Among these patients, 7 were admitted twice for epistaxis. The demographics, administrative history, post-history and associated diseases, treatment and complications were analyzed. Noninterventional treatment comprised of nasal packing and local electrocauterization; interventional treatment included surgery and embolization., Results: The mean age of the patients enrolled was 53.4 years. Men outnumbered women in a rate of 3:1. The mean length for hospital stays was 8.1 days for noninterventionally-treated patients, 11.8 days for interventionally-treated patients. Emergency room visit prior to admission was noted in 68.6% of the patients. Hypertension, nasopharyngeal carcinoma (NPC) after radiotherapy, a history of nasal operations and smoking were four major associated diseases. The failure rate to control the epistaxis was 26.7% for noninterventional treatments and 16.7% for interventional treatments. The complication rate was 2% for the entire study, and the mortality rate was 7.8%. All the mortal patients were post-irradiation NPC patients with internal carotid artery bleeding., Conclusions: Most epistaxis patients can be managed in a noninterventional manner. Interventional treatment is only warranted in those whose epistaxis persists after adequate noninterventional treatment. For internal carotid artery epistaxis in NPC patients, embolization should be performed as soon as possible.