# Performance of Sensor Data Process Offloading on 5G-Enabled UAVs
## 2 UAV as UE
### Cell Uplink Capacity and 5G UE  
Cellular networks, particularly 5G networks, differ significantly from other wireless technologies. In particular, 5G is divided into two components the 5G core and the new radio (NR) interface. Here the focus is on the NR interface and its capabilities. Numerous factors contribute to the achievable throughput data rates a UE can achieve when using 5G. The NR interface is a duplex communication system, and the spectrum utilization technique used for the separation of the transmitted signals from received signals is either time division duplexing (TDD) or frequency division duplexing (FDD) [19]. Although FDD was the predominant duplexing scheme in previous-generation cellular networks, TDD configurations now dominate 5G networks. Some of the reasons for the TDD selection are the decreased intra-cell interference and the fact that TDD is considerably more suited for the massive MIMO technology. Nevertheless, some critical parameters affect both TDD and FDD throughput capabilities. The most important ones are the bandwidth of the NR interface, the number of bits per symbol (determined by the modulation scheme, e.g., 25G QAM), and the code rate (R). Thus, Equation (1) is described in 3 GPP TS 38.306 [20] and is used to determine the throughput capabilities of a 5G NR interface. \[data\ rate\ (inMbps)=10^{-6}\cdot\sum_{j=1}^{J}(v_{Layers}^{(j)}.\] \[Q_{m}^{(j)}\cdot f^{(j)}\cdot R_{max}\cdot\frac{N_{PRB}^{(BW(j), \mu)}\cdot 12}{T_{s}^{\mu}}\cdot(1-OH^{(j)})) \tag{1}\]  
where \(J\) is the number of aggregated carriers, \(R_{max}=948/1024\), \(v_{Layers}^{(j)}\) is the maximum number of supported layers, \(Q_{m}^{(j)}\) is the number of bits per symbol in the maximum supported modulation order, \(f^{(j)}\) is the scaling factor, \(\mu\) is the numerology, \(T_{s}^{\mu}\) is the average OFDM symbol duration in a subframe for numerology \(\mu\), \(N_{PRB}^{(BW(j),\mu)}\) is the maximum resource block allocation in \(BW_{j}\) with numerology \(\mu\), and \(OH\) is the transmission overhead. Table 1 provides an example of such a calculation. It also describes the test network used in this study and refers to Section 3, where a collection of results relating to 5G-UAVs is presented. It should also be noted that Table 1 documents the case of a TDD configuration for the uplink resources. TDD separates the uplink and downlink signals in time, and here a 4-to-1 downlink-to-uplink ratio is used. Finally, it is also important to point out that the throughput calculation that Equation (1) refers to the case that a single UE is utilizing the cell. When multiple UEs are connected to a cell the resources are divided accordingly [19]. Nevertheless, 5G feedback signals can be used to make information, such as the cell load, available to the application layer. UL Enhancements  
The 5G standard has many configurations and features that enable uplink-heavy traffic, e.g., it supports uplink-heavy TDD patterns, and the theoretical capabilities are sufficient for handling the majority of uplink-heavy applications, which is also evident in Equation (1). Nevertheless, there are practical limitations when deploying TDD-based 5G networks. Multi-operator scenarios typically require the synchronized operation of adjacent networks, that is, compatible TDD frame structures have to be adopted among operators to avoid BS-BS and UE-UE interference. A common TDD frame in the mid-band frequencies of 3.4-3.8 GHz is defined to support eight timeslots in the downlink (DL) and two timeslots in the uplink (UL). An example of such a configuration is shown in Table 1 and yields 94 Mbps in the uplink. However, state-of-the-art applications across multiple fields, such as virtual reality, concert entertainment, robotics, machine vision, and the combination of some, such as enhanced teleoperation, are documented to require from 100 Mbps to 10 Gbps in extreme scenarios. For that reason, there are multiple efforts to support enhanced uplink configurations in 5G.