In this paper, we observe a practical real-life 2-sections heterogeneous microwave radio-relay (RR) network comprising classic SDH and SDH NGN architecture, hybrid parallel and mutually independent transmission of native-Ethernet and TDM services, as well as all-IP network part, to experimentally benchmark them with the former testing of a 5-sections RR system connecting the same endpoints, with the goal to verify the previous results. Specifically, the main task of the both works was to answer whether quite a diverse RR system could satisfy the quality norms for Ethernet based services, meaning whether a tolerable RR unavailability will necessarily imply the according Ethernet QoS degradation? This question is addressed by the comprehensive in-service and out-of-service testing of an operational hybrid RR transmission system under test. After the undertaken extensive practical testing and appropriate analysis of the achieved results, it came out that the impact of RR - level impairments that determine the performance prediction, affected the Ethernet QoS to the extent of BER approaching the acceptability threshold values defining (un) availability. High consistency of the new RR system test results was found with the previous results, which therefore verifies the appropriateness of this approach.

Microwave line-of-sight radio relay (RR) systems are a constitutive part of a telecom operator transport network, as an alternative to optical transmission systems when the latter are not technically possible or rational to implement. Nowadays, RR links are quite often used in the access network for connecting mobile radio base stations, thus also enabling traffic aggregation, and so on. In this paper, we focus on a practical, real-life, five-section heterogeneous RR network, comprising classic synchronous digital hierarchy (SDH) and SDH new generation network (NGN) architecture, hybrid parallel and mutually independent transmission of native Ethernet and TDM services, and all-IP network parts. Specifically, the main task of this work is to answer whether such a diverse RR system could satisfy the quality norms for Ethernet-based services, meaning whether a tolerable RR unavailability will necessarily imply the according Ethernet quality of service (QoS) degradation. This question is addressed by the comprehensive in-service and out-of-service testing of an operational hybrid RR transmission system. After extensive practical testing and appropriate analysis of the achieved results, it came out that the impact of RR-level impairments that determine the performance prediction affected the Ethernet QoS to the extent that BER values increased to the acceptability threshold values. We believe that the preliminary results reported here could serve as a hint and a framework for a more comprehensive cross-layer test strategy in terms of both test diversity and repeating rate, which contemporary network operators need to implement in order to enable the appropriate quality of experience for users of their services.

In this paper, we address practical wander measurements, which are usually regarded as less important than the jitter ones, though sometimes unjustifiably, as wander, if accumulated steadily, can seriously harm the bit-error-rate performance. With this respect, we firstly present the mechanisms of jitter and wander generation in digital transmission systems, and then provide an overview of standard functions that quantify these impairments according to relevant ITU-T recommendations, primarily focusing wander, which is usually regarded as less important than jitter and so sometimes neglected though its excessive values, too, can harm the transmission performance. Measurements were accomplished on live 155 Mbit/s SDH microwave radio-relay transmission system, encompassing 4 hops. The analysis of the obtained wander test results well reflects the health of the synchronization system.