{'fraction_non_alphanumeric': 0.018898931799506986, 'fraction_numerical': 0.018077239112571898, 'mean_word_length': 4.71830985915493, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
V2V Communications under the Shadowing of Multiple Big Vehicles

Vehicle to vehicle (V2V) communications using dedicated short range communications (DSRC) are considered as promising technology for enhancing road safety. However, the V2V communications see a challenge from obstruction of big vehicle such as big bus or truck. Based on our measurement, the big vehicle can cause signal loss from 10 to 15 dB. It makes the communication range shorter and reduces the safety message dissemination capability. In this paper, we analyze the impact of multiple big vehicles shadowing on the V2V communication. We propose a model which takes into account both geometric and stochastic shadowing of multiple big vehicles. Based on the proposed model, we derive the average length of the shadow region and the shadowing loss caused by multiple big vehicles. It is revealed that when the number of big vehicles increases from 1 to 25 vehicle per km, the shadow region increases from 50 m to more than 400 m on the road. Furthermore, the shadowing loss causes the packet delivery ratio of a typical car reducing from 90% to 20% or 50%, depending on whether the big vehicles are on the same or the next lane of this typical car.