Towards dynamic adaptation in broadcasting with hybrid rateless codes

There are many situations, such as in training and education, in which there is a frequent need to distribute large files to many clients, e.g., operating system boot images or raw data files. To carry out such distribution efficiently, we use wireless broadcast and a hybrid coding technique that combines forward coding using weak LT Codes with a feedback phase at the end, which allows concluding the process faster with lower computing cost than traditional LT codes. However, for the sake of scalability, in the feedback phase a scheduler bounds the maximum number of clients that can communicate feedback in each given cycle and schedules them. Moreover, using a shorter or longer feedback phase also impacts on the number of simultaneous clients in feedback mode, resulting in more or less impact of the scheduler and more or less effectiveness of the feedback itself. In this short paper we briefly describe a recently developed prototype and we summarize some preliminary results confirming the advantage of using scheduled feedback. Moreover, we discuss the interplay between duration of the feedback phase and clients scheduling as a line for future research in scheduling-coding co-design.