Completion delay reduction in lossy feedback scenarios for instantly decodable network coding

In this paper, we study the effect of packet feedback loss events on the broadcast completion delay performance of instantly decodable network coding. These feedback loss events result in a continuous lack of knowledge about the reception status at different subsets of receivers. This lack of knowledge creates a challenge in selecting efficient packet combinations in subsequent transmissions. To solve this problem, we first identify the different possibilities of unheard feedback events at the sender and determine their probabilities. Given these probabilities and the nature of the problem, we design three partially blind instantly decodable network coding approaches that perform coding decisions similar to the algorithms proposed in [1], [2], but on blindly updated graphs to account for unheard feedback events. These three approaches are then compared through extensive simulations. Results show that re-considering all the attempted packet requests, with unheard feedback, in subsequent coding decisions can achieve a tolerable degradation against the perfect feedback performance for relatively high feedback loss probabilities.