A Multi-hop Information Broadcast Protocol In Distributed Vehicular Networks

With the application of vehicular networks, traffic efficiency has been greatly improved, but the number of people dead from car accidents per year is not significantly decreased. It is because in the initial stage of vehicular networks applications, most of the information transmission operated in mobile carriers cooperated cellular networks. One of the shortcomings of this transmission is that the delay time is very long, so it is not applicable for transmitting alarm information. That's why research on the alarm information transfer protocol is particularly important. The way to transmit alarm information through multi-hop broadcast transmission can reduce the delay effectively, and multi-hop information broadcast protocol studies have now become hot research issues in vehicular networks.Multi-hop information broadcast protocols can be divided into three categories: based on the probability, based on count and location-based protocols. Through research, location-based multi-hop information broadcast protocols are much more suitable for distributed vehicular networks. After analyzing the strengths and weaknesses of the other algorithms, an alternated multi-hop information broadcast protocol (AMBP) is proposed, which combines some characteristics of distributed vehicular networks. AMBP is one of sender-oriented multi-hop information broadcast protocols based on location. Vehicle selects the next hop relay node and calculates alternately transmission gate value by querying the neighbor information table that contains information about the vehicle nodes. The frames are divided into two types: reliable data frames and unreliable data frames. The AMBP takes different transmission policies based on the relationships between frame lengths and the transmission gate values. When the alarm information data frame length is less than the alternant transmission value gate, only unreliable data frames will be sent, otherwise, reliable data frames and unreliable data frames will be broadcasted alternately. The AMBP ensures that the transmission delay is reduced with the guaranty of reliability.Experiments results show that comparing with Slotted-p-persistence and EMPR, AMBP does have certain advantages in reducing both packet loss rate and delay time. In addition, AMBP reduces delay jitter amplitude and performs more stable, so it is more suitable for distributed vehicular networks environment.