A cooperative approach for amplify-and-forward differential transmitted reference IR-UWB relay systems

Abstract

This paper proposes a novel cooperative approach for two-hop amplify-and-forward (A&F) relaying that exploits both the signal forwarded by the relay and the one directly transmitted by the source in impulse-radio ultra-wideband (IR-UWB) systems. Specifically, we focus on a non-coherent setup employing a double-differential encoding scheme at the source node and a single differential demodulation at the relay and destination. The log-likelihood ratio based decision rule is derived at the destination node. A semianalytical power allocation strategy is presented by evaluating a closed-form expression for the effective signal to noise ratio (SNR) at the destination, which is maximized by exhaustive search. Numerical simulations show that the proposed system outperforms both the direct transmission with single differential encoding and the non-cooperative multi-hop approach in different scenarios.Index Terms-Impulse-radio (IR), ultra-wideband (UWB) communications, differential transmitted reference (DTR), amplify and forward (A&F) relaying, log-likelihood ratio test

Balanced Performance Between Energy-Delay and Bit Error Rate in UAV Relay Networks

“…It is clearly seen that the highest SNR, at * γ(w j )[n 3 ], enhanced the bit error rate result, and this result confirms the theoretical analysis, as high SNR calculates from optimal power allocation. This result agrees with previous studies [53], which indicate that the power allocation ϕ i is an effective metric for enhancing UAV performance. Fig.…”

Joint Power Allocation and Path Selection for Multi-Hop Noncoherent Decode and Forward UWB Communications

“…Related Work. Noncoherent receivers have been applied to the context of relaying networks (see e.g., [19], [20], and [21]). In [19], a dual-hop two-way network is discussed wherein two devices exchange information through a single DF relay employing a code-multiplexing TR (CM-TR) signal structure.…”

“…However, a few limitations arise, namely: i) the relays have to be ordered before transmission starts, which increases the communication overhead; ii) in the specific dual-hop case, the performance is severely degraded when the link connecting either the source with the relay or the relay with the destination exhibits poor quality, and iii) the power allocation (PA) across the transmitting nodes is given in closed-form only for the dual-hop and through a sub-optimal recursive algorithm for the multi-hop, whereas the DF case (introduced for performance comparison) is solved through a demanding exhaustive search. In the scheme recently proposed in [21], the signals from both the relayed and direct paths are combined at the destination through a decision rule based on log-likelihood ratio (LLR) test. Significant performance gain is achieved with respect to both the direct transmission using single differential encoding and the NCR scheme of [20], even though the proposed semi-analytical PA strategy makes the extension to the multi-hop case infeasible.…”

Spectral Efficiency Optimization with Distributed Beamforming in UWB Based Implant Body Area Networks

“…While aforementioned work mainly focused on the narrowband cases, it is not straightforward to apply for the impulse-based UWB cases due to the special properties of UWB signaling such as analog transmission and dense resolvable multipath. Thus, some extensions of cooperative transmission strategies to UWB systems have been known in literature [8]- [11]. However, the problem of distributed beamforming regarding SE for UWB based BANs is still an open issue.…”