Packet Retransmission Schemes and Trials for Broadcast Services in Mobile Scenarios

With the escalating prevalence of datacasting, live streaming and high-quality video consumption on mobile devices, there arises an increasing demand for a cost-effective and reliable approach to transmit large volumes of such content to extensive audiences. While broadband mobile networks can increase capacity through denser base stations and higher frequencies, the linear pace of facility development makes it difficult to match the non-linear growth of the service throughput. Terrestrial Broadcast has proven itself to be significantly more efficient in transmitting popular video streams to mobile devices over a large area. However, due to its downlink-only nature, it falls short of delivering consistently reliable services. Hence, the convergence of terrestrial broadcast and broadband mobile networks has resurfaced as a pertinent topic for consideration. In this paper, terrestrial broadcast is adopted as the main pipe to transmit streaming services to mobile phones, with a 5th generation mobile communications (5G) new radio (NR) mobile carrier employed to provide complementary packet loss retransmission service, ensuring a seamless service experience. First, a cross-standard packet retransmission (CPR) scheme is proposed based on 5G broadcast and 5G NR Systems. Corresponding protocols and schemes are introduced, and a prototype system is realized. CPR is able to support delay-insensitive datacasting services very well, yet its higher layer convergence poses challenges for supporting delay-sensitive real-time services. To address this, a MAC-layer homogeneous packet retransmission (HPR) scheme is proposed. The basic principle is to utilize the carrier aggregation mechanism of 5G, modifying the protocols to enable one carrier to simulate broadcast while maintaining unicast in another carrier. In HPR, packet retransmission can be done at the MAC layer, reducing the retransmission delay to within 5 microseconds. Simulation and trial results are presented based on the proposed schemes.