Performance Analysis of DCW-Based Improved TCP Variant for Safety Message Broadcast in VANETs

Abstract

Considering highly dynamic nature of a vehicular network, timely dissemination of safety messages is required by vehicles to form and maintain an ad hoc network. As CAMs are periodically broadcasted, an ample amount of CAMs on the channel can lead to collision, thus leaving no scope for EDM dissemination. To cope up with this issue, optimal safety message dissemination is essential for a vehicular network to perform efficiently. The paper proposes a DCW-based improved TCP variant for safety message broadcast over the network. The number of backlogged messages at the nearest RSU is considered as the governing factor for dynamically adapting the CW size at the vehicle’s end. CW size plays an important role in managing broadcast of safety messages in VANETs. Round trip time is considered as the key parameter for estimating the number of safety messages at the nearest RSU. Simulation is performed considering three different vehicle’s transmission range (200–500 m). It is worth noting that, the proposed I-TCP variant outperforms the existing fixed CW schemes in terms of congestion probability for all the values of transmission range. Moreover, it can be evident that, for fixed CW size, lower transmission range should be preferred over the larger transmission range.