Method for enabling multiple vehicles to broadcast message simultaneously through multi-channel CSMA

Abstract

The invention relates to a method for enabling multiple vehicles to broadcast a message simultaneously through multi-channel CSMA. The method comprises the steps that (1) N channels which do not overlap each other are set in advance; (2) each vehicle node keeps monitoring the N channels; (3) whether an idle channel list is empty or not is checked when the vehicle nodes prepare to broadcast and emit an emergent information frame; (4) waiting a time interval lasting for at least one inter-frame space is conducted and whether RSS is smaller than ST all the time or not is checked before the vehicle nodes actually broadcast and emit the emergent information frame; (5) whether the RSS is smaller than the ST all the time is checked at any moment in a random access rollback period; (6) one used channel is marked as 'a channel used last time'. Compared with the prior art, the method for enabling the multiple vehicles to broadcast the message simultaneously through the multi-channel CSMA has the advantages that the spectral efficiency is improved through the multi-channel CSMA protocol integrating FDMA and / or CDMA, so that the information transmission delay of the vehicle nodes in the vehicle environment with a large density can be obviously reduced.

Description

technical field [0001] The present invention relates to the wireless communication technology of the Internet of Vehicles and its application field, in particular to a combination of FDMA and / or CDMA and CSMA, which utilizes multi-channel carrier sense multiple access (Multi-channel Carrier Sense Multiple Access, referred to as multiple Channel CSMA) mechanism to realize the method of multi-vehicles broadcasting emergency safety messages at the same time in the Internet of Vehicles. Background technique [0002] When broadcasting emergency information in the Vehicular Ad-hoc Network (VANET for short), the following important problems are faced: due to the highly correlated time selection of forwarding broadcast information between adjacent nodes, there are serious channel contention and collisions; More importantly, due to the existence of a large number of hidden nodes, it is difficult to guarantee the reliable distribution of broadcast information. To solve the above prob...

AI Technical Summary

Problems solved by technology

[0002] When broadcasting emergency information in the Vehicular Ad-hoc Network (VANET for short), the following important problems are faced: due to the highly correlated time selection of forwarding broadcast information between adjacent nodes, there are serious channel contention and collisions; More importantly, due to the existence of a large number of hidden nodes, it is difficult to ensure the reliable distribution of broadcast information

[0004] However, CSMA / CA still has the following shortcomings that need to be improved: 1) The RTS frame (or CTS frame) itself is also a broadcast frame transmitted by the transmitting node according to the carrier sense technology, and they themselves may be received due to the hidden node problem. The node collides with the RTS frame (or CTS frame) sent by another transmitting node

3) Emergency safety information is usually a short frame. When a vehicle node occupies the entire frequency domain channel in a certain time slot to broadcast emergency information according to CSMA / CA, transmitting a short information frame in the entire bandwidth is an important factor for frequency domain resources. Therefore, when in a dense vehicle environment, according to a large number of experimental results, using CSMA / CA or some existing improved protocols based on CSMA / CA may still cause some nodes to wait too long Large delay, even network congestion