A Survey on Radio Resource Allocation for V2X Communication

Table 2

Comparison of the existing underlaying RBs sharing based-user clustering/grouping in V2X services.

Ref.	Unicast/broadcast	Objectives	Scenarios	User types	Allocation constraints	Power control/allocation	Allocation process	Methods/theory	RB sharing
[34]	Unicast	Minimize the total power transmission and latency reliability	Urban	V-UEs	Queue length	PA	Nonorthogonal RBs are allocated for V2V-UEs in different clusters	Karush–Kuhn–Tucker theory	N V2V-UEs
[35]	Broadcast	Maximizing the sum rate capacity of the system	—	V-UEs	Capacity	—	Nonorthogonal RBs are allocated to user in different clusters	Kuhn–Munkres method	N V-UEs
[36]	Broadcast	Maximize the sum rate of the tr. V-UEs reliability for rx. V-UEs	Highway	V2V-UEs	OP	—	Orthogonal RBs are allocated in each zone; Nonorthogonal RBs are allocated in different zones	Greedy algorithm	N V2V-UEs
[37]	Unicast	Maximize the sum V2I reliability of V2V	Multilane freeway	V2V-UEs V2I-UEs	OP	PA	Nonorthogonal RBs are allocated to V2V-UEs in the same cluster; Orthogonal RB is allocated to V2I-UEs	Graph theory	1 V2I-UEs; N V2V-UEs