Buffer-Aided Relaying with Adaptive Link Selection

TL;DR

This paper introduces a buffer-aided relaying protocol with adaptive link selection that dynamically chooses transmission links based on channel conditions, significantly improving throughput in relay networks.

Contribution

It proposes a novel adaptive link selection protocol with buffer management, providing optimal policies and delay bounds for relay networks.

Findings

Achieves higher throughput than fixed-schedule relaying.

Provides optimal link selection and power allocation strategies.

Offers delay bounds and buffer overflow prevention methods.

Abstract

In this paper, we consider a simple network consisting of a source, a half-duplex decode-and-forward relay, and a destination. We propose a new relaying protocol employing adaptive link selection, i.e., in any given time slot, based on the channel state information of the source-relay and the relay-destination link a decision is made whether the source or the relay transmits. In order to avoid data loss at the relay, adaptive link selection requires the relay to be equipped with a buffer such that data can be queued until the relay-destination link is selected for transmission. We study both delay constrained and delay unconstrained transmission. For the delay unconstrained case, we characterize the optimal link selection policy, derive the corresponding throughput, and develop an optimal power allocation scheme. For the delay constrained case, we propose to starve the buffer of the relay by choosing the decision threshold of the link selection policy smaller than the optimal one and derive a corresponding upper bound on the average delay. Furthermore, we propose a modified link selection protocol which avoids buffer overflow by limiting the queue size. Our analytical and numerical results show that buffer-aided relaying with adaptive link selection achieves significant throughput gains compared to conventional relaying protocols with and without buffers where the relay employs a fixed schedule for reception and transmission.