Recently, there have been large numbers of research related to ITS (Intelligent Transport System). The major specification to realize ITS network is RC-005 using band frequency 5.8GHz. However it is difficult to connect if something disturbs Line-of-Sight (LOS) between communication devices due to characteristic of radio. In this paper, we propose a communication system based on approaches of temporal backup and frequency backup to increase communication stability and to cover wider area. We implement the prototype system and conduct some experiment using them. The result shows that temporal backup and frequency backup are effective in terms of data arrival rate and stable communication. We conclude in case of Non Line-of-Sight (NLOS) communication, temporal backup and frequency backup are efficient.