# Mobile Network Operators' Assessment Based on Drive-Test Campaign in Urban Area for iPerf Scenario
## 2 Drive Test Campaign
### iPerf Tool  
The iPerf tool is used for network performance measurement, testing, and tuning. It is free (i.e., based on Berkeley Software Distribution (BSD) license) and available for various operating systems, including CentOS Linux, FreeBSD, macOS, OpenBSD, Android, other Linux distributions, and Windows. The iPerf is compatible with various protocols, i.e., TCP, UDP, and Stream Control Transmission Protocol (SCTP) with both Internet Protocol (IP) version 4 (IPv4) and 6 (IPv6), and offers a range of customizable parameters. This tool is a staple for network administrators and engineers seeking to troubleshoot network problems, enhance performance, and undertake network experiments. Furthermore, the iPerf plays a crucial role in the performance testing and benchmarking of various network devices. In December 2023, the iPerf3-16 was released [26; 31; 32].  
Tests using the iPerf application were aimed at examining the stability and performance of the radio transmission link. They were carried out for two types of ISO/OSI  
Figure 3: Drive-test cars with R&S Smart Bechmarker [35].  
(International Organization for Standardization/Open Systems Interconnection reference model) transport layer protocols, i.e., TCP and UDP. The set data collected during tests were sequenced into UL and DL streams. This approach allows us to present the behavior of applications using TCP and UDP.  
TCP provides connection transmission using acknowledgment mechanisms for uniquely numbered transferred packets called three-way handshakes. It means that the established connection is open for the duration of data transmission, which guarantees a relatively high degree of reliability of flow control connections and increases transmission security. It comes at the cost of information overhead on packet numbering and the need to check the correct transmission of each packet, which reduces the efficiency of data transfer. TCP supports the applications for which the certainty of data delivery is crucial, requiring transfer integrity control, but not time-critical, such as applications based on the following protocols, Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Secure Shell (SSH), Simple Mail Transfer Protocol (SMTP), and Internet Message Access Protocol (IMAP) 4 [45].  
UDP is a connectionless protocol without mechanisms to control the correctness of data flow, which affects the transfer speed and efficiency. UDP implementation ensures faster data transfer, but there is no guarantee of data delivery. This protocol is used by real-time applications, mainly those that exchange large volumes of traffic and do not expect confirmations. It is used primarily by videoconferences, data streaming, and network gaming, as well as applications based on Voice over Internet Protocol (VoIP) or Domain Name System (DNS) [46].  
The parameter values adopted in the iPerf tests are contained in Table 3. In TCP, the following test profile was used during iPerf testing: 3 streams of 40 Mbps (7 s transfer time) and 3 streams of 8 Mbps each (5 sec transfer time) for DL and UL, respectively.  
UDP is mainly used for network stress testing because TCP automatically limits the throughput to adapt to the available bandwidth. To this aim, a bandwidth for UDP should be chosen far above what the connection can handle, e.g., if a user wants to stress a 10 Mbps connection, he/she should send about 100 Mbps of traffic [31]. Hence, the Lost Datagrams Rate (LDR) for UDP obtained in the test is very high compared to TCP.