Measurements to Study the Coexistence of Private LTE TDD Networks in 2.3 GHz Band

Abstract

Private wireless networks have recently gained interest in many business applications. Use of 4G and 5G technologies for private network deployments has become feasible recently. Finnish Transport and Communications Agency Traficom began to grant licenses for private mobile Time Division Duplex (TDD) networks on frequency band 2300-2320 MHz in 2020. In this study, the coexistence of two 4G TDD networks is investigated through an extensive measurement campaign. The laboratory test setup developed to conduct the interference measurement campaign can be used to study 4G and 5G TDD technologies in frequency bands below 4 GHz. Networks using TDD technology are recommended to use synchronized frame configurations to avoid interference. Private network applications and requirements differ between user organisations and hence the uplink and downlink data rate requirements are different and may need different TDD frame configurations. This paper studies interference between adjacent private networks, which have same or different TDD frame configurations. Measurement results indicate that non-synchronized networks produce interference and significant decrease in data throughput in neighboring networks.

Field Measurements to Study the Co-Existence of Geographically Limited Local Industrial Mobile TDD Networks

“…Interfered UL speed is decreased by 50 % when interfering power increases 10 dB above the threshold. These levels were in line with the earlier laboratory measurements [15]. On all field locations DL speed decreased, although no DL to DL interference was observed.…”

“…Field trial results confirm that the comprehensive laboratory measurement results [15] can be used as a basis for interference estimations. The results reveal the challenges in the planning of local 4G or 5G networks using overlapping frequencies and TDD technology.…”

“…The authors previously conducted an extensive laboratory measurement campaign to obtain an understanding on how the different frame configurations affect the interference between local networks [15]. Results of laboratory measurements conformed to the possibility of severe decrease in data throughput if the TDD frame configurations of two local networks are not synchronized, which was also noticed in simulations presented in [13].…”

“…The main objective of the presented field measurement campaign was to confirm that the laboratory measurement results of LTE local network systems using 2.3 GHz TDD technology in [15] and simulations such as [13] are valid in Severe throughput capacity reduction may occur when base station transmitter DL timeslots overlap adjacent network base station UL received timeslots. On the three closest locations propagation was line-of-sight and DL to UL interference was observed at the victim base station.…”