Adaptive hierarchical cooperative communication using energy harvesting relay

Dynamic interference‐limited relay sharing in cognitive radio networks by using hierarchical modulation

“…Therefore, we give an approximation to it in the next section. The error probabilities of other conditions are similarly achieved as follows: From (20) we have…”

“…Hierarchical modulation (HM), also named unequal error protection modulation, is a kind of adaptive modulation in which we can modulate different symbols onto different layers of constellation [4,[16][17][18][19]. In [20], we applied this modulation technique to a cooperative system with two data sources and a relay utilising this method in order to transmit both sources' information data to the destination simultaneously. In [21], we utilised HM in radio cognitive context in order to improve secondary user's (SU's) performance and compensate the degradation of primary users' (PUs') performance and even improve it by allowing the existing relay to send information data of both PU and SU.…”

“…It is worth noting that the basic concepts of HM has been introduced in [23] where the main idea is dividing the information bits into two or more classes with different degrees of protection. In [20], we introduced the concept of using adaptive hierarchical communication as a technique that enables efficient sharing of relaying nodes among two users having equal priority, in terms of QoS, in the network.…”

“…Therefore, most of the time the SU transmits data with low power via direct link only (without relay) which leads to low QoS for the SU and low utilisation of the relay channel. In [21], we expand our work, [20], to the case that the two users are not in the same level of priority in the network and apply HM into a relay-based CR network in which the relay is shared with both PU and SU.…”

Optimisation of secrecy rate in cooperative device to device communications underlaying cellular networks

“…In cooperative communication, the users help each other in relaying information to increase the communication rates, communication reliability and system capacity [3]. Several schemes of cooperative communications have been investigated which select or share relays under different conditions such as interference or consumed power constraints [4, 5]. Comparing with traditional fixed terminal, the relaying device can realise the full potential of cooperation [6].…”