Chapter 5 - Network Coding and User Cooperation for Streaming and Download Services in LTE Networks

Abstract

This chapter proposes the usage of network coding and user cooperation for existing LTE networks. Long Term Evolution (LTE) networks are supposed to use Raptor codes for content distribution such as download and streaming services over the air towards mobile devices. Like other FEC technologies, Raptor codes introduce redundancy which increases the total bandwidth of the system and also increase the energy consumption of mobile devices with good channel characteristics due to ongoing repair messages for devices with bad channel characteristics. Raptor codes substantially increase the perceived delay for each user which can be problematic, especially for streaming services. Therefore user cooperation with network coding is proposed to support streaming and download services in future mobile communication systems and overcoming the bandwidth and energy issues. The simulation results show that local retransmissions can save up to 80% of redundant information of the cellular link, as long as there are at least two cooperative mobile devices. The results also show that network coding can save more than half of the traffic in the short-range link as long as there are four devices in the cooperation cluster. Larger gains can be achieved by increasing the number of cooperating devices. To make the local retransmission in the short-range link more efficient, network coding is considered for the local retransmission and a local retransmission protocol is proposed. Reducing the traffic on the short-range link can reduce the overall energy consumption, as well as reduce the time that is needed to complete the exchange of packets locally, especially in dense traffic networks.