  Cognitive radio (CR) technology enables an intelligent wireless communication
system. CR provides an efficient solution for the inefficient spectrum
utilization by allowing dynamic and opportunistic spectrum access. In designing
CR networks, the main challenge is how to increase network throughput while
protecting the performance of licensed primary radio networks (PRNs) and
keeping the interference between primary users (PUs) and cognitive users (CUs)
within a prescribed threshold. In this work, we develop a multi-cast routing
algorithm that based on the expected transmission count metric (ETX), which
implemented as a metric combined with minimum spanning tree (MST) and shortest
path tree (SPT) schemes according to the various traffic loads in CRN to
determine the path selection method and used the probability of Success (POS)
metric for the channel assignment that used the required transmission time and
the channel availability time in choosing unified channel. The main objective
of our algorithm is to reduce the total number of the expected packet
transmissions (with retransmissions) needed for successfully forwarding a data
packet to a specific group of destinations and provide guarantees on the
chances of a successful transmission over a given channel. This metric is
capable to capture the CRNs environment, in which the channel availabilities
are diversity and dynamically changing due to the dynamic and uncertainty
activity of PUs. Our proposed protocol achieves high-throughput and packet
delivery rate (PDR) through a joint channel assignment and path selection to
the specific destinations. Simulation results is used to demonstrate the
effectiveness of our proposed algorithm in terms of throughput and packet
delivery rate compared to other existing multi-cast routing protocols over
different network conditions by using matlab as a simulations.
