Transmission sequence reconstruction and allocation for VANET

In this paper, reconstruction and allocation transmission sequences are investigated for addressing media access control (MAC) without feedback in Vehicular Ad-hoc Network (VANET). Global Navigation Satellite Systems (GNSS) based code allocation is a great solution. It tessellates the geographic region to be covered into regular hexagonal quantization cell. All users access to their location information at marked time instances through GNSS. The transmission sequences are pre-assigned to the location cells and then dynamically assigned to the users. It also proposed a concept of sequence reuse that is akin to frequency reuse. A drawback of GNSS-based code allocation is the average user throughput (AUT) is relatively low. Transmission sequence reconstruction and allocation (TSRA) based on GNSS-based code allocation is proposed. Firstly, in each superframe T, each user acquires user irrepressibility (UI) sequence according to GNSS-based mechanism in the first period to obtain the information of neighbors in the same cell cluster; users in different direction use half of the superframe T respectively. Secondly, users reconstruct a set of UI sequences according to the number of neighbors in the same cell cluster. Then, users acquire a reconstructed sequence according to the order of the users' first successful “1” in the first period. The performance of TSRA is compared with GNSS-based code allocation by ns-2 with the vehicle mobility data from the Simulation of Urban Mobility (SUMO). The simulation results show that the AUT of TSRA is better than GNSS-based code allocation in a relatively sparser distributed network.