Cooperative multicasting based on superposition and layered coding

Abstract

Cooperative diversity plays an important role in combating channel fading and increasing reliability of wireless communication links. The main purpose of cooperative diversity is to transmit the same data from multiple sources. Hence, there is no inherent capability in the cooperative diversity schemes to deal with scalable types of data, for example, scalable video coded signals. The authors introduce a two-phase cooperative multicast scheme based on superposition coding to transmit scalable video signals. The new scheme mixes the superposition with cooperative diversity, and chooses the right parameters in both schemes to enhance the system's multicast capability. This study also derives an exact closed-form expression of the average multicast group throughput in case of Rayleigh flat fading channel. The closed-form expression allows system designers to choose the correct cooperation and superposition parameters to satisfy the network operator needs. Simulations show that, in addition to the additional degrees of freedom resulting from using cooperation with superposition, the proposed scheme outperforms the conservative scheme and schemes solely exploiting cooperative relaying or superposition. Simulations show that the new scheme can increase the average network throughput more than four times compared to the conservative scheme.

Superposition network coded cooperation for wireless networks

“…Cooperative communication is a practical approach to exploit spatial diversity . This technique has been widely investigated from industrial perspective and is considered as a desirable and promising approach to next generation wireless technologies . The fundamental idea of cooperative communication is to use the cooperation among a group of distributed nodes to form a virtual multiple antenna system .…”

“…In fact, by transmitting a single signal in each time slot, the time and frequency mismatches at the receiver are easier to determine than those of simultaneous transmission‐based schemes and can be corrected by using a simple phased‐locked loop device at the receiver . In order to provide the lowest possible time delay, we use a technique called superposition coded cooperation (SCC) . The basic idea of SCC is to transmit a signal, made of a suitable combination of multiple signals, to destination .…”

“…The transmitter allocates its transmit power to the signals in a defined manner, adds them together and then transmits the resulted composite signal in its transmission phase . In , for providing higher spatial diversity gain in a network, a cooperative multicast scheme with one source node is proposed, where the source node, using SCC, broadcasts a composite signal, made of two messages, to a group of receivers. To achieve optimal diversity‐multiplexing trade‐off, a two‐way multi‐relay cooperative scheme based on superposition coding is proposed in .…”