Non-stationary time-varying vehicular channel characteristics for different roadside scattering environments.

With the deep integration of wireless communication technology and automobile industry, vehicular communication has become one of the key technologies supporting the development of Internet-of-vehicle. Due to the high-speed mobility of vehicles and the rapid change of the propagation environments, vehicle-to-vehicle (V2V) wireless communication channels are generally non-stationary. Meanwhile, the variability of V2V channel characteristics is obvious in different scattering environments. Focusing on these research points, this paper presents the analysis and comparison of V2V channel characteristics for different scattering scenarios based on a series of 5.9 GHz channel measurements. The measurement data are collected from the iron bridge, the soundproof wall, and the road lamp scenarios. The stationary time and frequency are investigated on the basis of method of local scattering functions. The classical channel characteristics, including power delay profile, Ricean K-factor, root means square (RMS) delay spread and RMS Doppler spread are extracted following the propagation principle. Furthermore, considering the source and birth-death process of multi-path components (MPCs) in different scattering propagation environments, cluster identification and statistical results are presented and compared. The different values of the channel parameters and the different performance of the channel under different scattering environments can help us understand the V2V channel deeply. The research results can be used for the design and optimization of vehicular communication systems in different scattering environments.

[Epidemiological survey on malaria situation in Motuo County of Tibet, China].

OBJECTIVE: To make an epidemiological investigation on malaria in Motuo County, Linzhi Prefecture of Tibet. METHODS: In July of the year 2006, the following activities were conducted in 2 selected villages from each of the three townships, i.e., Motuo, Dexing and Beibeng: malaria history survey among inhabitants in recent 2 years; collection of blood samples of inhabitants for examining malaria parasites, IFAT and detecting G6PD, respectively; mosquito collection in human dwellings and cattle shelters at night and various resting sites at day-time; mosquito collection by outdoor human baiting capture; classification and composition calculation of mosquito species and man biting rates; ELISA for detecting sporozoite infection of Anopheles. RESULTS: The mean rate of two-year malaria history was 8.98% (118/1314) and the parasite rate was 3.13% (38/1216, all P. vivax) in the inhabitants. The parasite positive rate among the feverish patients was 7.14% (3/42). IFAT revealed a malaria antibody rate of 40.24% (472/1173). The G6PD deficiency rate was 1.74% (21/1208). Five hundred and thirteen anopheline mosquitoes were caught. They were An. maculatus (474) which occupied 92.4% (474/513), An. peditaeniatus (35), An. kochi (3) and An. sinensis (1). The mean indoor density of An. maculatus was 4.75/night in human houses, and 69.5/night in cattle shelters. The outdoor human biting rate was 22.75/half-night/person, and the sporozoite rate of An. maculatus in anopheline saliva glands was 0 by ELISA. CONCLUSION: Motuo County is an endemic area of vivax malaria with An. maculatus as the potential vector.