Improved Tomlinson–Harashima Precoding for Ultra Reliable Communication in Intelligent Transportation Systems

Algorithm 1

User scheduling based on the greedy algorithm.

Input: number of transmitting antennas , signal-to-noise ratio (SNR) , number of candidate users , candidate user channel matrix , number of target users ;
Output: channel matrix of selected users .
	Step 1. Initialization: Set candidate user set , selected user set , channel matrix , which is an empty matrix;
	Step 2. Calculate the spectrum utilization of each user in the candidate user, and select the user with the largest spectrum utilization. ;
	Step 3. Update the sets. , , and update the channel matrix ;
	Step 4. The users in the updated set are combined with the selected users to form a new joint channel matrix. Then, calculate the spectrum utilization of the joint channel, and select the user with the largest combined spectrum utilization;
	Step 5. Repeat step 3 until the number of target users is selected;
	Step 6. End and output the channel matrix of the selected users .