• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.9C
• /
• pp.887-895
• /
• 2009

This paper proposes a cooperative power allocation with the use of partial channel information (e.g., the average signal-to-noise ratio (SNR) and transmit correlation) in multi-cell dual-hop multi-input single-output (MISO) relay systems. In a dual-hop MISO relay channel, it is desirable to allocate the transmit power between dual-hop links to maximize the end-to-end capacity. We consider the maximization of the end-to-end capacity of a dual-hop MISO relay channel under sum-power constraint. The proposed scheme adaptively allocates the transmit power considering the average channel gain of the target relay and the transmit correlation of the desired and inter-relay interference channel from adjacent relays. It is shown by means of upper-bound analysis that the end-to-end capacity can be maximized by making the angle difference of the principal eigenvectors of the desired and inter-relay interference channel orthogonal in highly-correlated channel environments. Finally, the performance of the proposed scheme is verified by computer simulation.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39B no.4
• /
• pp.216-227
• /
• 2014

Mechanical Relay (McR) is a relaying architecture to enable data communications, where it can endure the transportation delay and intermittent disconnection. Every kind of vehicular infrastructures can be readily utilized for the mechanical relaying in the manner of moving natures, which brings the most significant consequences compared to conventional relaying schemes. In this paper, we analyze the ergodic network throughput of McR in wireless line networks (WLN) to compare the results between employing McRs and direct multi-hopping through the users without McRs. We demonstrate the McR scheme that are not only Ve-SISO but also Ve-SIMO/MISO. The numerical results of ergodic network throughputs contribute to the trade-off relation depending on the speed v of McRs, intensity factors ${\lambda}_u$ and ${\lambda}_r$, and the methods of how McRs are utilized.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.4
• /
• pp.1889-1910
• /
• 2017

This paper investigates a protocol so-called Adaptive Harvest Then Transmit (AHTT) for wireless powered communication networks (WPCNs) in multiple-input single-output (MISO) downlink systems, which assists in transmitting signals from a multi-antenna transmitter to a single-antenna receiver. Particularly, the power constrained relay is supplied with power by utilizing radio frequency (RF) signals from the source. In order to take advantage of multiple antennas, two different linear processing schemes, including Maximum Ratio Combining (MRC) and Selection Combination (SC) are studied. The system outage capacity and ergodic capacity are evaluated for performance analysis. Furthermore, the optimal power allocation is also considered. Our numerical and simulation results prove that the implementation of multiple antennas helps boost the energy harvesting capability. Therefore, this paper puts forward a new way to the energy efficiency (EE) enhancement, which contributes to better system performance.