Cooperative overlay secondary transmissions exploiting primary retransmissions

Abstract

We introduce an overlay cooperative cognitive radio scheme, in which the secondary network transmits only during the retransmissions of the primary network. The secondary network makes use of multiple relays in order to increase its performance compared to a non-cooperative scenario. Moreover, the secondary operates without harming the performance of the primary network. Different cooperative protocols are employed and associated with hybrid automatic repeat request mechanisms. Our results show that the incremental decode-and-forward technique allows the secondary network to achieve the highest throughput among the considered methods, at the cost of a very small degradation in the performance of the primary network.

On the performance of cognitive full-duplex relaying under spectrum sharing constraints

“…Motivated by the great benefits acquired through cognitive radio and cooperative techniques, several works analyzed the performance of cooperative cognitive networks under spectrum sharing constraints, as for instance [18][19][20][21][22][23][24][25][26][27][28][29]. Nevertheless, a common characteristic of these works is that all proposed schemes operate under HD mode with exception of [29].…”

“…Even though we acknowledge the extensive contributions of the previous works [18][19][20][21][22][23][24][25][26][27][28], it should be emphasized that they only considered HD relays, which is spectrally inefficient due to multiplexing loss. Thus, conversely to all previous works, in [29], the authors considered a scenario in which the secondary cooperative network utilizes a FD relay subject to self-interference.…”

“…In [22], the authors ignore the direct link but include the interference of the primary network in their analysis of outage probability showing the impact on performance because of the interference from the primary network. The authors in [23] exploit the primary network retransmissions in order to increase performance of the underlaid network. The results show that cooperation at the underlaid layer considerably increases performance without harming the performance of the primary network.…”

Optimal resource allocation for cognitive radio networks with primary user outage constraint

“…The M relays are considered to be in a cluster, so that they are assumed to be approximately at the same position. This assumption simplifies the analysis and can represent a number of practical scenarios [19,21,22]. Time division multiple access (TDMA)-based protocol is used for the secondary transmissions, and three different transmission models for the secondary system are considered in this article.…”

“…The work in [18] restrained the transmit powers of secondary transmitter and secondary relay under individual primary outage constraint for PU. In [19], the authors introduced a new cooperative transmission scheme for overlay cognitive radio in which the secondary network exploits the primary retransmissions without requiring global CSI. Further in [20], the primary outage constraint due to secondary transmitter and secondary relay was jointly considered for the first time, and a closed-form solution for optimal PA and relay selection was derived in DF cognitive relay networks.…”