# Selecting Remote Driving Locations for Latency Sensitive Reliable Tele-Operation
## 3 Selecting Driving Locations for Multiple Paths
If a driver in a location, for example \(d_{1}\), controls the vehicle from the start to the end, the latency between \(d_{1}\) and \(B_{11}\), the final base station, is likely to be very large so that the performance of remote control may degrade and even cause accidents. Thus, it is necessary for different drivers in different driving locations to control the vehicle for different segments of the paths to satisfy the safety requirement such as a latency limit. Since we cannot deploy the drivers to every base station in the area due to the management cost, we need to select a set of driving locations in the area in such a way that the selected locations satisfy the requirement of the remote driving system. In this paper, we extend the single path case to the _multiple_ path case and select the driving locations for multiple paths. For this problem, we assume that the sequence of base stations of the multiple paths are given. The requirement of the remote controlling system may differ depending on many factors such as management cost and latency limit. Thus, we consider the following two objectives, which are likely to incorporate various requirements of different remote driving systems. * Objective I: Selecting the smallest number of driving locations while satisfying a given latency threshold. * Objective II: Selecting a set of driving locations that minimize the latency between the vehicles and driving locations when the number of driving locations is fixed. In the first objective, we assume that the remote driving is safe if the latency is under a certain threshold. Under this assumption, we want to minimize the number of remote driving locations to reduce the management cost. Furthermore, if there are multiple sets of driving locations of same size that satisfy the latency constraint, we may want to choose the set of driving locations that has the smallest latency. In the second objective, the number of  
Figure 3: Remote drivers and base stations in a remote driving system. driving locations is fixed, which means that the cost of maintaining the driving locations is fixed. With the given budget of driving locations, we want to reduce the latency as much as possible. It should be noted that depending on various situations, the latency constraint or the number of driving locations may vary. Actually, in [7], we have proposed an algorithm called \"Remote driver Selection for Multiple Paths (RDSMP)\", which selects the driving locations when a latency threshold is given. Basically RDSMP focuses on the objective I. However, RDSMP does not consider the latency further when it finds a certain number of driving locations. To be specific, there can be different sets of the same number of driving locations that satisfy the latency constraints. Then, we might want to have a set of driving locations that can reduce the latency as much as possible. In other words, even though the selected driving locations satisfy the latency constraints, it would be better to reduce the latency as much as possible by selecting other sets of driving locations of the same size. Furthermore, in this paper, we newly formulate Objective II on top of Objective I to deal with many other situations. Thus, in this paper, we propose a comprehensive set of algorithms for the above two objectives. For all the algorithms, we assume that the candidate driving locations are given instead of assuming that any location in the area can be a driving location. It is quite reasonable to assume the candidate locations because we might not be able to build a remote driving facility in any location due to many reasons such as rental costs, geographic constraints, and communication infrastructure. Basically, we choose the driving locations from the candidate set. Before we describe the algorithms in detail, we first define some notations at Table 2. Furthermore, we use the term \"driving location\" and a \"driver\" interchangeably because selecting a driving location means selecting a driver in that location.