# Service-Oriented Cooperation Policies for Intelligent Ground Vehicles Approaching Intersections
## 4 Design of Cooperation Policies and Algorithms
### Composite Policies: Taking Advantages of Different Ones Above  
To utilize the advantage of different policies, we further composite these different single policies in pairs to improve both the passing-through efficiency of vehicles (H) and the traffic throughput at an intersection. Typically, in this study all eight aforementioned policies have been implemented. In the following, expected effects of these different policies under the same traffic situation are shown in Figure 5 are explained, and as shown in Figures 6 and 7, Figures 6c,d and 7b-d show five new ones. It is important to note that symbols \"SQ\" and \"MQ\" in the names of these policies are relevant to the PAP and MLAP, respectively. Although different factors have been considered, the performance of each policy still needs to be further verified. (1) Four FAFP-Based Policies  
FAFP-SV: Regard the whole intersection as a single S-CS; When the intersection is free, only choose and authorize the whole intersection to one single vehicle that applies to pass through at the earliest. As shown in Figure 6a, for the first arrival vehicle \(v_{1}\), its parameter \(<S,L,L,1>\) represents that it will travel straightly with a lowest priority, no priority promotion, and is the first vehicle authorized to pass. Similarly, \(v_{4}\) and \(v_{6}\) are the second vehicle and the third one authorized to turn right at this intersection. FAFP-SQ: Regard the whole intersection as a single S-CS; When the intersection is free, only choose and authorize the whole intersection to one vehicular platoon in which the earliest arrived vehicle is. As an example, Figure 6b shows that \(v_{1}\), \(v_{2}\), and \(v_{3}\) on the same lane are authorized as a platoon, and, \(v_{2}\) will turn left while the other two will pass straightly. FAFP-SQ-SV: Regard an intersection as a set of adjacent S-CSs; Each time, after choosing and authorizing a platoon with the manner same to FAFP-SQ, iteratively choose and authorize the earliest vehicle that is passable with those remnent-free S-CSs, from all left lanes. For the traffic situation in Figure 5, \(v_{1}\), \(v_{2}\), and \(v_{3}\) will be authorized as FAFP-SQ, but, because \(\gamma_{2}\) is always not occupied, \(v_{4}\) will be solely authorized to pass simultaneously, as shown in Figure 6c. FAFP-MQ: Regard an intersection as a set of adjacent S-CSs; Each time, after choosing and authorizing a platoon with the manner same to FAFP-SQ, from the other vehicles and lanes, iteratively choose and authorize a platoon that includes the earliest arrival vehicle, and all members of which do not require any authorized S-CS. For example, the passable platoon on the same lane covers \(v_{4}\) and \(v_{5}\) as shown in Figure 6d. Figure 5: A Traffic Scene. (2) Four QoS-Oriented Policies  
HQEP-SV: Regard the whole intersection as a single S-CS; Processing all queues with GPI mechanism, and then choose the head vehicle with current highest priority (namely, Highest priority, or Medium priority when there is no vehicle (H)) to authorize. For the cases that all head vehicles on different lanes own a same priority, this policy will finally degrade to be FAFP-SV policy. As shown in Figure 7a, since \(\gamma_{2}\) has been authorized to \(v_{4}\) and \(v_{4}\) will delay \(v_{7}\), so the priority of \(v_{4}\) and \(v_{6}\) should be promoted to guarantee \(v_{4}\) releasing obtained critical sections as soon as possible, and \(v_{6}\) becomes a vehicle (H);  
HWFP-SQ: Regard the whole intersection as a single S-CS; When the intersection is free, select and authorize one platoon from the lane that owns a maximum weight value, as illustrated in Figure 7b. When all lanes have the same weight, this policy degrades to be a FAFP-SQ policy;  
HWFP-SQ-SV: Regard an intersection as a set of adjacent S-CSs; Each time, after choosing and authorizing a platoon from the lane that has the maximum weight value, iteratively choose and authorize the vehicle with current highest priority from other lanes that does not require any authorized S-CS.