Optimal Multiplexed Erasure Codes for Streaming Messages with Different Decoding Delays This paper considers multiplexing two sequences of messages with two different decoding delays over a packet erasure channel. In each time slot, the source constructs a packet based on the current and previous messages and transmits the packet, which may be erased when the packet travels from the source to the destination. The destination must perfectly recover every source message in the first sequence subject to a decoding delay T_mathrmv and every source message in the second sequence subject to a shorter decoding delay T_mathrmule T_mathrmv. We assume that the channel loss model introduces a burst erasure of a fixed length B on the discrete timeline. Under this channel loss assumption, the capacity region for the case where T_mathrmvle T_mathrmuB was previously solved. In this paper, we fully characterize the capacity region for the remaining case T_mathrmvu003e T_mathrmuB. The key step in the achievability proof is achieving the nontrivial corner point of the capacity region through using a multiplexed streaming code constructed by superimposing two singlestream codes. The converse is proved by obtaining a genieaided bound when the channel is subject to a periodic erasure pattern where each period consists of a lengthB burst erasure followed by a lengthT_mathrmu noiseless duration.

Capacity Results for Erasure Broadcast Channels with Intermittent Feedback Recently, we showed that, rather surprisingly, the capacity region of the twouser erasure broadcast channel with global delayed channel state information (CSI) can be achieved with singleuser delayed CSI only. More precisely, we assumed one receiver does not provide its channel state to the other two nodes (the other receiver and the transmitter), while the other receiver reveals its state globally with unit delay. In this work, we consider a more general setting in which feedback links are intermittent. To be precise, at any time instant, each receiver broadcasts its CSI, and this information either becomes available to the other two nodes or gets erased. For this setting, we develop a new set of outer bounds to capture the intermittent nature of the feedback links. These outer bounds depend on the probability that both feedback links are erased rather than the individual erasure probability of each feedback link. This result matches our earlier findings for the singleuser delayed CSI scenario. We also provide a capacityachieving recursive communication protocol for the scenario in which feedback links are fully correlated.