Abstract
In this paper, we evaluate end-to-end outage probability of a multi-hop decode-and-forward relaying protocol in underlay cognitive radio network. In the proposed protocol, named COOP, secondary nodes including source and relays have to harvest radio-frequency energy from multiple secondary power beacons, and adjust their transmit power, follows a pre-determined interference threshold given by multiple primary users. To enhance the outage performance for the secondary network under an joint constraint of the interference threshold, Rayleigh fading channel and hardware noises caused by imperfect transceiver hardware, the secondary relays on the source-destination path cooperate to forward the source data to the destination. Particularly, they attempt to receive the source data from their previous nodes, and forward it to the secondary destination if requested. Moreover, whenever the destination cannot receive the source data successfully, a successful relay that has the shortest distance to the destination is selected for retransmission. Due to usage of the cooperative transmission, the proposed COOP protocol obtains better performance, as compared with the corresponding multi-hop relaying one (denoted DIRECT) which only uses direct transmission at each hop. We evaluate the outage performance of COOP and DIRECT via both simulation and theory. The obtained results present a significant performance enhancement, as comparing COOP with DIRECT.
Highlights
Radio frequency energy harvesting (RF-EH) [1,2,3,4,5] is a new and promising technique for wireless communication applications in future when the number of wireless devices exponentially increases.In addition, RF-EH allows a transmitter to simultaneously send energy and information to its intended receivers via wireless signals
To mainly focus on the impact of the number of hops (M), the hardware impairment level of the data links, the number of the power beacons (N), the number of the primary users (K), and the fraction of time ( α) on OPCOOP and OPDIRECT, the other system parameters are fixed in all the simulations as follows: the position of the power beacons are fixed at (0.5, 0.2); the primary users are located at (0.5, −0.5); the path-loss exponent ( β) is set to 3, the value of the conversion efficiency (μ) is assigned by 0.5; the target rate (Cth ) is fixed by 0.5; the maximum e2e delay
We observe that slope of OPCOOP is higher than that of OPDIRECT because COOP obtains higher diversity gain
Summary
Radio frequency energy harvesting (RF-EH) [1,2,3,4,5] is a new and promising technique for wireless communication applications in future when the number of wireless devices exponentially increases.In addition, RF-EH allows a transmitter to simultaneously send energy and information to its intended receivers via wireless signals. As proposed in Reference [6], a relay node can receive both data and energy from a source by allocating a fraction of the received signal power for EH, and remaining one for data transmission. This method is named as power-splitting (PS) RF-EH, and is widely applied. As analyzed in References [19,20], co-channel interference from ambient sources can support the green energy as well as prolong lifetime for wireless communication systems. To support the wireless energy for a large number of wireless nodes in a certain area, the published literature [21,22,23,24,25] has proposed power beacon (PB)-aided
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