3 research outputs found
Performance Analysis and Cooperation Mode Switch in HARQ-based Relaying
We study the optimal, in terms of power-limited outage probability (OP), placement of the relay and investigate
the effect of relay placement on the optimal cooperation mode of the source and the relay nodes. Using hybrid automatic repeat request (HARQ) based relaying techniques, general expressions for the OP and the average transmit power are derived. The results are then particularized to the repetition time diversity (RTD) protocol. The analytical expressions are used to find the
transmit powers minimizing the power-limited OP. Our results demonstrate that adaptive power allocation reduces the OP significantly. For instance, consider a Rayleigh fading channel, an OP of 10^-3 and a maximum of 2 RTD-based retransmissions. Then, compared to equal power allocation, the required transmission signal-to-noise ratio (SNR) is reduced by 5 dB, if adaptive
power allocation is utilized. Another important observation is that, depending on the relay positions and the total power budget, the system should switch between the single-node transmission mode and the joint transmission mode, in order to minimize the outage probability
On the Performance of the Relay-ARQ Networks
This paper investigates the performance of relay networks in the presence of
hybrid automatic repeat request (ARQ) feedback and adaptive power allocation.
The throughput and the outage probability of different hybrid ARQ protocols are
studied for independent and spatially-correlated fading channels. The results
are obtained for the cases where there is a sum power constraint on the source
and the relay or when each of the source and the relay are power-limited
individually. With adaptive power allocation, the results demonstrate the
efficiency of relay-ARQ techniques in different conditions.Comment: Accepted for publication in IEEE Trans. Veh. Technol. 201