# TARS: A Novel Mechanism for Truly Autonomous Resource Selection in LTE-V2V Mode 4
## 2 Related Work  
A substantial research effort has been conducted aiming at efficient resource allocation for LTE-based vehicular communication. A two-stage distributed resource allocation technique was presented in [16] to assist the outside network coverage scenario of LTE-based V2V communication. Initially, vehicles are classified in subpools according to their orthogonal directions, followed by Resource Block (RB) assignment based on the directions in which they are moving. Automobiles traveling in the same direction are granted the same set of resources. Secondly, in order to avoid packet collision between vehicles traveling parallel to each other, a channel-sensing mechanism is employed. The proposed scheme provides better Collision Avoidance (CA) for ARS mode of resource allocation in LTE. The authors in [14] proposed a collision-avoidance scheme for ARS in vehicular communication based on LTE. The performance of ARS is significantly improved by the proposed algorithm. To inform the neighbor vehicles about the reserved data packets, SA information is piggybacked on the data packets in the reservation phase, resulting in improved reliability and minimized data packet collisions. In [17], an optimized resource allocation for LTE-V2X networks was achieved, keeping different sizes of periodic broadcast packets in consideration. The number of automobiles that can be assigned when the parameters are upgraded for messages of various extents was valuated. The effect of some transmission parameters on the count of vehicles was examined. The authors presented an improved resource selection approach in [18] for V2V communication, which delivers an ARS grounded on a defined frame structure, involving SA and data transmission. Sensing results are utilized to mitigate collisions in a secondary approach. The proposed mechanism is analogous to the LTE Release 12 side link communication with reference to throughput and the probability of collision. A novel collective ARS and scheduled resource assignment mechanism was introduced in [19]. The goal is to augment the aggregate of the data values of users. The presented approach takes the user's Proximity Service (ProSe) Per-Packet Priority (PPPP) and the reliability of the communication into account, while satisfying the Quality of Service (QoS) of Vehicular User Equipment (V-UE) and Pedestrian User Equipment (P-UE). The authors presented a D2D resource allocation and power control (DRAPC) strategy for sharing spectrum and allocating power for D2D communications in [20]. There were four resource sharing models proposed, in which the Cellular User Equipment (CUE) and Machine-to-Machine (M2M) pairings were related to one another in one-to-one, one-to-many, many-to-one, and many-to-many ways. M2M communication minimizes the network traffic burden because the communication does not pass through eNodeB. Radio Resource Management (RRM) for V2X was presented in [21], which offers reliability and latency when assigning resources to vehicles and is based on D2D communication. To ensure the sum-rate and reliability constraints, the authors explored a unicast communication paradigm. In a highway scenario, the signal power and buffer size were chosen as the key parameters for V2X communication. To improve the network's performance, an algorithm for relay-based two-hop D2D communication was developed in [22]. A resource allocation approach with minimal interference was presented, which can be used in cellular networks with two-hop D2D communications. eNodeB assigns cellular users' resources to D2D users, based on signal-to-interference-plus-noise ratio (SINR) with the aim of increasing system throughput. In [23], the authors presented a method for jointly optimizing relay selection, power control, and spectrum allocation. The technique involves a refined jointly optimized relay selection problem, while taking care of the constraints of EE. To reduce power consumption,the problem is represented as a bipartite graph between the UEs and a set of relays.