German technology company Rohde & Schwarz has initiated the world’s first dynamic single-frequency network (SFN) with FeMBMS signals in the lab.
The trial takes place within the framework of the 5G Today research project and in cooperation with the Institute for Communications Technology of the Braunschweig Technical University.
LTE Broadcast, also known as Further evolved Multimedia Broadcast Multicast Service (FeMBMS), was specified in 3GPP Release 14 in mid-2017. The upgraded standard defines new options for broadcasting to LTE-enabled mobile user equipment such as smartphones and tablets. For the first time, it allows high power high tower (HPHT) applications in downlink only mode.
The new features make it possible to utilise the full signal bandwidth for multicast/broadcast applications. Moreover, 3GPP Release 14 defines an extended cyclic prefix (corresponding to the guard interval in DVB-T/T2) and modes to enable operation without SIM cards, which is necessary for the broadcast application.
The Rohde & Schwarz FeMBMS transmission addresses broadcast applications for video and IP data in HPHT topologies with bandwidths of 5 MHz and 10 MHz. With the trial set-up, the company wants to demonstrate the potential held by 5G Broadcast for applications such as TV services delivered to mobile user equipment and connected cars, and for IoT applications.
Like all SFN networks, the Rohde & Schwarz LTE Broadcast SFN network requires synchronisation information, which is made available to each FeMBMS transmitter via the M1 application protocol. The sync information is generated by an Evolved Packet Core (EPC) and completed by an incoming IP-based video data stream, which is either generated or encoded and multiplexed by a headend. SYNC timestamps are inserted into the data stream to generate the M1 user plane data. This data is routed via IP networks to the FeMBMS transmitters, which transmit the signal simultaneously. The FeMBMS signal is received by a software defined radio (SDR).
Currently, a major European 5G field trial is being established in Germany as part of the 5G Today Bavarian research project. Under the leadership of the Institute for Broadcast Technology (IRT), project partners Kathrein and Rohde & Schwarz are investigating large-scale TV broadcast transmissions in FeMBMS mode over 5G Broadcast networks. The project is supported by Telefónica Germany and Bayerischer Rundfunk (BR), the Bavarian affiliate of German public broadcaster ARD. BR is providing two HPHT sites near Munich for the field trial.